diff --git a/lib/wallet/cryptoApi.ts b/lib/wallet/cryptoApi.ts
index 855afbb4e..ec20dd964 100644
--- a/lib/wallet/cryptoApi.ts
+++ b/lib/wallet/cryptoApi.ts
@@ -21,12 +21,12 @@
  */
 
 
-import {PreCoin} from "./types";
-import {Reserve} from "./types";
+import {PreCoin, Coin, ReserveRecord, AmountJson} from "./types";
 import {Denomination} from "./types";
 import {Offer} from "./wallet";
 import {CoinWithDenom} from "./wallet";
 import {PayCoinInfo} from "./types";
+import {RefreshSession} from "./types";
 
 interface RegistryEntry {
   resolve: any;
@@ -228,7 +228,7 @@ export class CryptoApi {
   }
 
 
-  createPreCoin(denom: Denomination, reserve: Reserve): Promise<PreCoin> {
+  createPreCoin(denom: Denomination, reserve: ReserveRecord): Promise<PreCoin> {
     return this.doRpc("createPreCoin", 1, denom, reserve);
   }
 
@@ -257,4 +257,17 @@ export class CryptoApi {
   rsaUnblind(sig: string, bk: string, pk: string): Promise<string> {
     return this.doRpc("rsaUnblind", 4, sig, bk, pk);
   }
+
+  createWithdrawSession(kappa: number, meltCoin: Coin,
+                        newCoinDenoms: Denomination[],
+                        meltAmount: AmountJson,
+                        meltFee: AmountJson): Promise<RefreshSession> {
+    return this.doRpc("createWithdrawSession",
+                      4,
+                      kappa,
+                      meltCoin,
+                      newCoinDenoms,
+                      meltAmount,
+                      meltFee);
+  }
 }
diff --git a/lib/wallet/cryptoLib.ts b/lib/wallet/cryptoLib.ts
index 9a77b3d74..7969682b4 100644
--- a/lib/wallet/cryptoLib.ts
+++ b/lib/wallet/cryptoLib.ts
@@ -22,13 +22,21 @@
 "use strict";
 
 import * as native from "./emscriptif";
-import {PreCoin, Reserve, PayCoinInfo} from "./types";
+import {
+  PreCoin, PayCoinInfo, AmountJson,
+  RefreshSession, RefreshPreCoin, ReserveRecord
+} from "./types";
 import create = chrome.alarms.create;
 import {Offer} from "./wallet";
 import {CoinWithDenom} from "./wallet";
 import {CoinPaySig} from "./types";
 import {Denomination} from "./types";
 import {Amount} from "./emscriptif";
+import {Coin} from "../../background/lib/wallet/types";
+import {HashContext} from "./emscriptif";
+import {RefreshMeltCoinAffirmationPS} from "./emscriptif";
+import {EddsaPublicKey} from "./emscriptif";
+import {HashCode} from "./emscriptif";
 
 
 export function main(worker: Worker) {
@@ -61,7 +69,7 @@ namespace RpcFunctions {
    * reserve.
    */
   export function createPreCoin(denom: Denomination,
-                                reserve: Reserve): PreCoin {
+                                reserve: ReserveRecord): PreCoin {
     let reservePriv = new native.EddsaPrivateKey();
     reservePriv.loadCrock(reserve.reserve_priv);
     let reservePub = new native.EddsaPublicKey();
@@ -224,4 +232,82 @@ namespace RpcFunctions {
     }
     return ret;
   }
-}
+
+
+  function createWithdrawSession(kappa: number, meltCoin: Coin,
+                                 newCoinDenoms: Denomination[],
+                                 meltAmount: AmountJson,
+                                 meltFee: AmountJson): RefreshSession {
+
+    let sessionHc = new HashContext();
+
+    let transferPubs: string[] = [];
+
+    let preCoinsForGammas: RefreshPreCoin[][] = [];
+
+    for (let i = 0; i < newCoinDenoms.length; i++) {
+      let t = native.EcdsaPrivateKey.create();
+      sessionHc.read(t);
+      transferPubs.push(t.toCrock());
+    }
+
+    for (let i = 0; i < newCoinDenoms.length; i++) {
+      let r = native.RsaPublicKey.fromCrock(newCoinDenoms[i].denom_pub);
+      sessionHc.read(r.encode());
+    }
+
+    sessionHc.read(native.RsaPublicKey.fromCrock(meltCoin.coinPub).encode());
+    sessionHc.read((new native.Amount(meltAmount)).toNbo());
+
+    for (let j = 0; j < kappa; j++) {
+      let preCoins: RefreshPreCoin[] = [];
+      for (let i = 0; i < newCoinDenoms.length; i++) {
+
+        let coinPriv = native.EddsaPrivateKey.create();
+        let coinPub = coinPriv.getPublicKey();
+        let blindingFactor = native.RsaBlindingKeySecret.create();
+        let pubHash: native.HashCode = coinPub.hash();
+        let denomPub = native.RsaPublicKey.fromCrock(newCoinDenoms[i].denom_pub);
+        let ev: native.ByteArray = native.rsaBlind(pubHash,
+                                                   blindingFactor,
+                                                   denomPub);
+        let preCoin: RefreshPreCoin = {
+          blindingKey: blindingFactor.toCrock(),
+          coinEv: ev.toCrock(),
+          publicKey: coinPub.toCrock(),
+          privateKey: coinPriv.toCrock(),
+        };
+        preCoins.push(preCoin);
+        sessionHc.read(ev);
+      }
+      preCoinsForGammas.push(preCoins);
+    }
+
+    let sessionHash = new HashCode();
+    sessionHash.alloc();
+    sessionHc.finish(sessionHash);
+
+    let confirmData = new RefreshMeltCoinAffirmationPS({
+      coin_pub: EddsaPublicKey.fromCrock(meltCoin.coinPub),
+      amount_with_fee: (new Amount(meltAmount)).toNbo(),
+      session_hash: sessionHash,
+      melt_fee: (new Amount(meltFee)).toNbo()
+    });
+
+    let confirmSig: string = native.eddsaSign(confirmData.toPurpose(),
+                                              native.EddsaPrivateKey.fromCrock(
+                                                meltCoin.coinPriv)).toCrock();
+
+    let refreshSession: RefreshSession = {
+      meltCoinPub: meltCoin.coinPub,
+      newDenoms: newCoinDenoms.map((d) => d.denom_pub),
+      confirmSig,
+      valueWithFee: meltAmount,
+      transferPubs,
+      preCoinsForGammas,
+    };
+
+    return refreshSession;
+  }
+
+}
\ No newline at end of file
diff --git a/lib/wallet/db.ts b/lib/wallet/db.ts
index 23cc9eb07..55e943393 100644
--- a/lib/wallet/db.ts
+++ b/lib/wallet/db.ts
@@ -25,7 +25,7 @@
  */
 
 const DB_NAME = "taler";
-const DB_VERSION = 7;
+const DB_VERSION = 8;
 
 /**
  * Return a promise that resolves
@@ -72,7 +72,7 @@ export function openTalerDb(): Promise<IDBDatabase> {
           if (e.oldVersion != DB_VERSION) {
             window.alert("Incompatible wallet dababase version, please reset" +
                          " db.");
-            chrome.browserAction.setBadgeText({text: "R!"});
+            chrome.browserAction.setBadgeText({text: "err"});
             chrome.browserAction.setBadgeBackgroundColor({color: "#F00"});
             throw Error("incompatible DB");
           }
diff --git a/lib/wallet/emscriptif.ts b/lib/wallet/emscriptif.ts
index 23014114a..7c08fdc45 100644
--- a/lib/wallet/emscriptif.ts
+++ b/lib/wallet/emscriptif.ts
@@ -119,10 +119,16 @@ var emscAlloc = {
     ['number', 'number', 'number', 'string']),
   eddsa_key_create: getEmsc('GNUNET_CRYPTO_eddsa_key_create',
     'number', []),
+  ecdsa_key_create: getEmsc('GNUNET_CRYPTO_ecdsa_key_create',
+                            'number', []),
   eddsa_public_key_from_private: getEmsc(
     'TALER_WRALL_eddsa_public_key_from_private',
     'number',
     ['number']),
+  ecdsa_public_key_from_private: getEmsc(
+    'TALER_WRALL_ecdsa_public_key_from_private',
+    'number',
+    ['number']),
   data_to_string_alloc: getEmsc('GNUNET_STRINGS_data_to_string_alloc',
     'number',
     ['number', 'number']),
@@ -181,7 +187,7 @@ interface ArenaObject {
 }
 
 
-class HashContext implements ArenaObject {
+export class HashContext implements ArenaObject {
   private hashContextPtr: number | undefined;
 
   constructor() {
@@ -590,6 +596,29 @@ export class EddsaPrivateKey extends PackedArenaObject {
 mixinStatic(EddsaPrivateKey, fromCrock);
 
 
+export class EcdsaPrivateKey extends PackedArenaObject {
+  static create(a?: Arena): EcdsaPrivateKey {
+    let obj = new EcdsaPrivateKey(a);
+    obj.nativePtr = emscAlloc.ecdsa_key_create();
+    return obj;
+  }
+
+  size() {
+    return 32;
+  }
+
+  getPublicKey(a?: Arena): EcdsaPublicKey {
+    let obj = new EcdsaPublicKey(a);
+    obj.nativePtr = emscAlloc.ecdsa_public_key_from_private(this.nativePtr);
+    return obj;
+  }
+
+  static fromCrock: (s: string) => EcdsaPrivateKey;
+}
+mixinStatic(EcdsaPrivateKey, fromCrock);
+
+
+
 function fromCrock(s: string) {
   let x = new this();
   x.alloc();
@@ -629,6 +658,16 @@ export class EddsaPublicKey extends PackedArenaObject {
 }
 mixinStatic(EddsaPublicKey, fromCrock);
 
+export class EcdsaPublicKey extends PackedArenaObject {
+  size() {
+    return 32;
+  }
+
+  static fromCrock: (s: string) => EcdsaPublicKey;
+}
+mixinStatic(EddsaPublicKey, fromCrock);
+
+
 function makeFromCrock(decodeFn: (p: number, s: number) => number) {
   function fromCrock(s: string, a?: Arena) {
     let obj = new this(a);
diff --git a/lib/wallet/query.ts b/lib/wallet/query.ts
index 77a4f8e35..fa78fe640 100644
--- a/lib/wallet/query.ts
+++ b/lib/wallet/query.ts
@@ -24,10 +24,6 @@
 "use strict";
 
 
-export function Query(db: IDBDatabase) {
-  return new QueryRoot(db);
-}
-
 /**
  * Stream that can be filtered, reduced or joined
  * with indices.
@@ -265,7 +261,7 @@ class IterQueryStream<T> extends QueryStreamBase<T> {
 }
 
 
-class QueryRoot {
+export class QueryRoot {
   private work: ((t: IDBTransaction) => void)[] = [];
   private db: IDBDatabase;
   private stores = new Set();
@@ -332,7 +328,7 @@ class QueryRoot {
   /**
    * Get one object from a store by its key.
    */
-  get(storeName: any, key: any): Promise<any> {
+  get<T>(storeName: any, key: any): Promise<T|undefined> {
     if (key === void 0) {
       throw Error("key must not be undefined");
     }
diff --git a/lib/wallet/types.ts b/lib/wallet/types.ts
index 91b329842..9ff8680ca 100644
--- a/lib/wallet/types.ts
+++ b/lib/wallet/types.ts
@@ -42,6 +42,30 @@ export class AmountJson {
 }
 
 
+export interface ReserveRecord {
+  reserve_pub: string;
+  reserve_priv: string,
+  exchange_base_url: string,
+  created: number,
+  last_query: number | null,
+  /**
+   * Current amount left in the reserve
+   */
+  current_amount: AmountJson | null,
+  /**
+   * Amount requested when the reserve was created.
+   * When a reserve is re-used (rare!)  the current_amount can
+   * be higher than the requested_amount
+   */
+  requested_amount: AmountJson,
+  /**
+   * Amount we've already withdrawn from the reserve.
+   */
+  withdrawn_amount: AmountJson;
+  confirmed: boolean,
+}
+
+
 @Checkable.Class
 export class CreateReserveResponse {
   /**
@@ -147,6 +171,13 @@ export interface PreCoin {
   coinValue: AmountJson;
 }
 
+export interface RefreshPreCoin {
+  publicKey: string;
+  privateKey: string;
+  coinEv: string;
+  blindingKey: string
+}
+
 
 /**
  * Ongoing refresh
@@ -173,20 +204,9 @@ export interface RefreshSession {
    */
   newDenoms: string[];
 
-  /**
-   * Blinded public keys for the requested coins.
-   */
-  newCoinBlanks: string[][];
 
-  /**
-   * Blinding factors for the new coins.
-   */
-  newCoinBlindingFactors: string[][];
+  preCoinsForGammas: RefreshPreCoin[][];
 
-  /**
-   * Private keys for the requested coins.
-   */
-  newCoinPrivs: string[][];
 
   /**
    * The transfer keys, kappa of them.
@@ -195,15 +215,6 @@ export interface RefreshSession {
 }
 
 
-export interface Reserve {
-  exchange_base_url: string
-  reserve_priv: string;
-  reserve_pub: string;
-  created: number;
-  current_amount: AmountJson;
-}
-
-
 export interface CoinPaySig {
   coin_sig: string;
   coin_pub: string;
diff --git a/lib/wallet/wallet.ts b/lib/wallet/wallet.ts
index 337ed8255..49e4e0a8d 100644
--- a/lib/wallet/wallet.ts
+++ b/lib/wallet/wallet.ts
@@ -27,21 +27,20 @@ import {
   IExchangeInfo,
   Denomination,
   Notifier,
-  WireInfo
+  WireInfo, RefreshSession, ReserveRecord
 } from "./types";
-import { HttpResponse, RequestException } from "./http";
-import { Query } from "./query";
-import { Checkable } from "./checkable";
-import { canonicalizeBaseUrl } from "./helpers";
-import { ReserveCreationInfo, Amounts } from "./types";
-import { PreCoin } from "./types";
-import { Reserve } from "./types";
-import { CryptoApi } from "./cryptoApi";
-import { Coin } from "./types";
-import { PayCoinInfo } from "./types";
-import { CheckRepurchaseResult } from "./types";
-import { Contract } from "./types";
-import { ExchangeHandle } from "./types";
+import {HttpResponse, RequestException} from "./http";
+import {QueryRoot} from "./query";
+import {Checkable} from "./checkable";
+import {canonicalizeBaseUrl} from "./helpers";
+import {ReserveCreationInfo, Amounts} from "./types";
+import {PreCoin} from "./types";
+import {CryptoApi} from "./cryptoApi";
+import {Coin} from "./types";
+import {PayCoinInfo} from "./types";
+import {CheckRepurchaseResult} from "./types";
+import {Contract} from "./types";
+import {ExchangeHandle} from "./types";
 
 "use strict";
 
@@ -50,29 +49,6 @@ export interface CoinWithDenom {
   denom: Denomination;
 }
 
-interface ReserveRecord {
-  reserve_pub: string;
-  reserve_priv: string,
-  exchange_base_url: string,
-  created: number,
-  last_query: number | null,
-  /**
-   * Current amount left in the reserve
-   */
-  current_amount: AmountJson | null,
-  /**
-   * Amount requested when the reserve was created.
-   * When a reserve is re-used (rare!)  the current_amount can
-   * be higher than the requested_amount
-   */
-  requested_amount: AmountJson,
-  /**
-   * Amount we've already withdrawn from the reserve.
-   */
-  withdrawn_amount: AmountJson;
-  confirmed: boolean,
-}
-
 
 @Checkable.Class
 export class KeysJson {
@@ -256,8 +232,8 @@ function isWithdrawableDenom(d: Denomination) {
 
 interface HttpRequestLibrary {
   req(method: string,
-    url: string | uri.URI,
-    options?: any): Promise<HttpResponse>;
+      url: string | uri.URI,
+      options?: any): Promise<HttpResponse>;
 
   get(url: string | uri.URI): Promise<HttpResponse>;
 
@@ -288,7 +264,7 @@ interface KeyUpdateInfo {
  * amount, but never larger.
  */
 function getWithdrawDenomList(amountAvailable: AmountJson,
-  denoms: Denomination[]): Denomination[] {
+                              denoms: Denomination[]): Denomination[] {
   let remaining = Amounts.copy(amountAvailable);
   const ds: Denomination[] = [];
 
@@ -330,10 +306,14 @@ export class Wallet {
    */
   private runningOperations: Set<string> = new Set();
 
+  q(): QueryRoot {
+    return new QueryRoot(this.db);
+  }
+
   constructor(db: IDBDatabase,
-    http: HttpRequestLibrary,
-    badge: Badge,
-    notifier: Notifier) {
+              http: HttpRequestLibrary,
+              badge: Badge,
+              notifier: Notifier) {
     this.db = db;
     this.http = http;
     this.badge = badge;
@@ -359,14 +339,14 @@ export class Wallet {
   updateExchanges(): void {
     console.log("updating exchanges");
 
-    Query(this.db)
-      .iter("exchanges")
-      .reduce((exchange: IExchangeInfo) => {
-        this.updateExchangeFromUrl(exchange.baseUrl)
-          .catch((e) => {
-            console.error("updating exchange failed", e);
-          });
-      });
+    this.q()
+        .iter("exchanges")
+        .reduce((exchange: IExchangeInfo) => {
+          this.updateExchangeFromUrl(exchange.baseUrl)
+              .catch((e) => {
+                console.error("updating exchange failed", e);
+              });
+        });
   }
 
   /**
@@ -376,19 +356,19 @@ export class Wallet {
   private resumePendingFromDb(): void {
     console.log("resuming pending operations from db");
 
-    Query(this.db)
-      .iter("reserves")
-      .reduce((reserve: any) => {
-        console.log("resuming reserve", reserve.reserve_pub);
-        this.processReserve(reserve);
-      });
+    this.q()
+        .iter("reserves")
+        .reduce((reserve: any) => {
+          console.log("resuming reserve", reserve.reserve_pub);
+          this.processReserve(reserve);
+        });
 
-    Query(this.db)
-      .iter("precoins")
-      .reduce((preCoin: any) => {
-        console.log("resuming precoin");
-        this.processPreCoin(preCoin);
-      });
+    this.q()
+        .iter("precoins")
+        .reduce((preCoin: any) => {
+          console.log("resuming precoin");
+          this.processPreCoin(preCoin);
+        });
   }
 
 
@@ -397,8 +377,8 @@ export class Wallet {
    * but only if the sum the coins' remaining value exceeds the payment amount.
    */
   private async getPossibleExchangeCoins(paymentAmount: AmountJson,
-    depositFeeLimit: AmountJson,
-    allowedExchanges: ExchangeHandle[]): Promise<ExchangeCoins> {
+                                         depositFeeLimit: AmountJson,
+                                         allowedExchanges: ExchangeHandle[]): Promise<ExchangeCoins> {
     // Mapping from exchange base URL to list of coins together with their
     // denomination
     let m: ExchangeCoins = {};
@@ -411,9 +391,9 @@ export class Wallet {
       let coin: Coin = mc[1];
       if (coin.suspended) {
         console.log("skipping suspended coin",
-          coin.denomPub,
-          "from exchange",
-          exchange.baseUrl);
+                    coin.denomPub,
+                    "from exchange",
+                    exchange.baseUrl);
         return;
       }
       let denom = exchange.active_denoms.find((e) => e.denom_pub === coin.denomPub);
@@ -425,7 +405,7 @@ export class Wallet {
         console.warn("same pubkey for different currencies");
         return;
       }
-      let cd = { coin, denom };
+      let cd = {coin, denom};
       let x = m[url];
       if (!x) {
         m[url] = [cd];
@@ -445,10 +425,12 @@ export class Wallet {
       handledExchanges.add(info.url);
       console.log("Checking for merchant's exchange", JSON.stringify(info));
       return [
-        Query(this.db)
-          .iter("exchanges", { indexName: "pubKey", only: info.master_pub })
-          .indexJoin("coins", "exchangeBaseUrl", (exchange) => exchange.baseUrl)
-          .reduce((x) => storeExchangeCoin(x, info.url))
+        this.q()
+            .iter("exchanges", {indexName: "pubKey", only: info.master_pub})
+            .indexJoin("coins",
+                       "exchangeBaseUrl",
+                       (exchange) => exchange.baseUrl)
+            .reduce((x) => storeExchangeCoin(x, info.url))
       ];
     });
 
@@ -467,38 +449,38 @@ export class Wallet {
     // under depositFeeLimit
 
     nextExchange:
-    for (let key in m) {
-      let coins = m[key];
-      // Sort by ascending deposit fee
-      coins.sort((o1, o2) => Amounts.cmp(o1.denom.fee_deposit,
-        o2.denom.fee_deposit));
-      let maxFee = Amounts.copy(depositFeeLimit);
-      let minAmount = Amounts.copy(paymentAmount);
-      let accFee = Amounts.copy(coins[0].denom.fee_deposit);
-      let accAmount = Amounts.getZero(coins[0].coin.currentAmount.currency);
-      let usableCoins: CoinWithDenom[] = [];
-      nextCoin:
-      for (let i = 0; i < coins.length; i++) {
-        let coinAmount = Amounts.copy(coins[i].coin.currentAmount);
-        let coinFee = coins[i].denom.fee_deposit;
-        if (Amounts.cmp(coinAmount, coinFee) <= 0) {
-          continue nextCoin;
-        }
-        accFee = Amounts.add(accFee, coinFee).amount;
-        accAmount = Amounts.add(accAmount, coinAmount).amount;
-        if (Amounts.cmp(accFee, maxFee) >= 0) {
-          // FIXME: if the fees are too high, we have
-          // to cover them ourselves ....
-          console.log("too much fees");
-          continue nextExchange;
-        }
-        usableCoins.push(coins[i]);
-        if (Amounts.cmp(accAmount, minAmount) >= 0) {
-          ret[key] = usableCoins;
-          continue nextExchange;
-        }
+      for (let key in m) {
+        let coins = m[key];
+        // Sort by ascending deposit fee
+        coins.sort((o1, o2) => Amounts.cmp(o1.denom.fee_deposit,
+                                           o2.denom.fee_deposit));
+        let maxFee = Amounts.copy(depositFeeLimit);
+        let minAmount = Amounts.copy(paymentAmount);
+        let accFee = Amounts.copy(coins[0].denom.fee_deposit);
+        let accAmount = Amounts.getZero(coins[0].coin.currentAmount.currency);
+        let usableCoins: CoinWithDenom[] = [];
+        nextCoin:
+          for (let i = 0; i < coins.length; i++) {
+            let coinAmount = Amounts.copy(coins[i].coin.currentAmount);
+            let coinFee = coins[i].denom.fee_deposit;
+            if (Amounts.cmp(coinAmount, coinFee) <= 0) {
+              continue nextCoin;
+            }
+            accFee = Amounts.add(accFee, coinFee).amount;
+            accAmount = Amounts.add(accAmount, coinAmount).amount;
+            if (Amounts.cmp(accFee, maxFee) >= 0) {
+              // FIXME: if the fees are too high, we have
+              // to cover them ourselves ....
+              console.log("too much fees");
+              continue nextExchange;
+            }
+            usableCoins.push(coins[i]);
+            if (Amounts.cmp(accAmount, minAmount) >= 0) {
+              ret[key] = usableCoins;
+              continue nextExchange;
+            }
+          }
       }
-    }
     return ret;
   }
 
@@ -508,8 +490,8 @@ export class Wallet {
    * pay for a contract in the wallet's database.
    */
   private async recordConfirmPay(offer: Offer,
-    payCoinInfo: PayCoinInfo,
-    chosenExchange: string): Promise<void> {
+                                 payCoinInfo: PayCoinInfo,
+                                 chosenExchange: string): Promise<void> {
     let payReq: any = {};
     payReq["amount"] = offer.contract.amount;
     payReq["coins"] = payCoinInfo.map((x) => x.sig);
@@ -539,18 +521,18 @@ export class Wallet {
       }
     };
 
-    await Query(this.db)
-      .put("transactions", t)
-      .put("history", historyEntry)
-      .putAll("coins", payCoinInfo.map((pci) => pci.updatedCoin))
-      .finish();
+    await this.q()
+              .put("transactions", t)
+              .put("history", historyEntry)
+              .putAll("coins", payCoinInfo.map((pci) => pci.updatedCoin))
+              .finish();
 
     this.notifier.notify();
   }
 
 
   async putHistory(historyEntry: HistoryRecord): Promise<void> {
-    await Query(this.db).put("history", historyEntry).finish();
+    await this.q().put("history", historyEntry).finish();
     this.notifier.notify();
   }
 
@@ -562,8 +544,7 @@ export class Wallet {
   async confirmPay(offer: Offer): Promise<any> {
     console.log("executing confirmPay");
 
-    let transaction = await Query(this.db)
-      .get("transactions", offer.H_contract);
+    let transaction = await this.q().get("transactions", offer.H_contract);
 
     if (transaction) {
       // Already payed ...
@@ -571,8 +552,8 @@ export class Wallet {
     }
 
     let mcs = await this.getPossibleExchangeCoins(offer.contract.amount,
-      offer.contract.max_fee,
-      offer.contract.exchanges);
+                                                  offer.contract.max_fee,
+                                                  offer.contract.exchanges);
 
     if (Object.keys(mcs).length == 0) {
       console.log("not confirming payment, insufficient coins");
@@ -584,8 +565,8 @@ export class Wallet {
 
     let ds = await this.cryptoApi.signDeposit(offer, mcs[exchangeUrl]);
     await this.recordConfirmPay(offer,
-      ds,
-      exchangeUrl);
+                                ds,
+                                exchangeUrl);
     return {};
   }
 
@@ -596,17 +577,15 @@ export class Wallet {
    */
   async checkPay(offer: Offer): Promise<any> {
     // First check if we already payed for it.
-    let transaction = await
-      Query(this.db)
-        .get("transactions", offer.H_contract);
+    let transaction = await this.q().get("transactions", offer.H_contract);
     if (transaction) {
-      return { isPayed: true };
+      return {isPayed: true};
     }
 
     // If not already payed, check if we could pay for it.
     let mcs = await this.getPossibleExchangeCoins(offer.contract.amount,
-      offer.contract.max_fee,
-      offer.contract.exchanges);
+                                                  offer.contract.max_fee,
+                                                  offer.contract.exchanges);
 
     if (Object.keys(mcs).length == 0) {
       console.log("not confirming payment, insufficient coins");
@@ -614,7 +593,7 @@ export class Wallet {
         error: "coins-insufficient",
       };
     }
-    return { isPayed: false };
+    return {isPayed: false};
   }
 
 
@@ -623,8 +602,7 @@ export class Wallet {
    * with the given hash.
    */
   async executePayment(H_contract: string): Promise<any> {
-    let t = await Query(this.db)
-      .get("transactions", H_contract);
+    let t = await this.q().get<Transaction>("transactions", H_contract);
     if (!t) {
       return {
         success: false,
@@ -645,14 +623,14 @@ export class Wallet {
    * then deplete the reserve, withdrawing coins until it is empty.
    */
   private async processReserve(reserveRecord: ReserveRecord,
-    retryDelayMs: number = 250): Promise<void> {
+                               retryDelayMs: number = 250): Promise<void> {
     const opId = "reserve-" + reserveRecord.reserve_pub;
     this.startOperation(opId);
 
     try {
       let exchange = await this.updateExchangeFromUrl(reserveRecord.exchange_base_url);
       let reserve = await this.updateReserve(reserveRecord.reserve_pub,
-        exchange);
+                                             exchange);
       let n = await this.depleteReserve(reserve, exchange);
 
       if (n != 0) {
@@ -667,15 +645,15 @@ export class Wallet {
             currentAmount: reserveRecord.current_amount,
           }
         };
-        await Query(this.db).put("history", depleted).finish();
+        await this.q().put("history", depleted).finish();
       }
     } catch (e) {
       // random, exponential backoff truncated at 3 minutes
       let nextDelay = Math.min(2 * retryDelayMs + retryDelayMs * Math.random(),
-        3000 * 60);
+                               3000 * 60);
       console.warn(`Failed to deplete reserve, trying again in ${retryDelayMs} ms`);
       setTimeout(() => this.processReserve(reserveRecord, nextDelay),
-        retryDelayMs);
+                 retryDelayMs);
     } finally {
       this.stopOperation(opId);
     }
@@ -683,18 +661,18 @@ export class Wallet {
 
 
   private async processPreCoin(preCoin: PreCoin,
-    retryDelayMs = 100): Promise<void> {
+                               retryDelayMs = 100): Promise<void> {
     try {
       const coin = await this.withdrawExecute(preCoin);
       this.storeCoin(coin);
     } catch (e) {
       console.error("Failed to withdraw coin from precoin, retrying in",
-        retryDelayMs,
-        "ms", e);
+                    retryDelayMs,
+                    "ms", e);
       // exponential backoff truncated at one minute
       let nextRetryDelayMs = Math.min(retryDelayMs * 2, 1000 * 60);
       setTimeout(() => this.processPreCoin(preCoin, nextRetryDelayMs),
-        retryDelayMs);
+                 retryDelayMs);
     }
   }
 
@@ -730,10 +708,10 @@ export class Wallet {
       }
     };
 
-    await Query(this.db)
-      .put("reserves", reserveRecord)
-      .put("history", historyEntry)
-      .finish();
+    await this.q()
+              .put("reserves", reserveRecord)
+              .put("history", historyEntry)
+              .finish();
 
     let r: CreateReserveResponse = {
       exchange: canonExchange,
@@ -754,8 +732,13 @@ export class Wallet {
    */
   async confirmReserve(req: ConfirmReserveRequest): Promise<void> {
     const now = (new Date).getTime();
-    let reserve: ReserveRecord = await Query(this.db)
-      .get("reserves", req.reservePub);
+    let reserve: ReserveRecord|undefined = await (
+      this.q().get<ReserveRecord>("reserves",
+                                  req.reservePub));
+    if (!reserve) {
+      console.error("Unable to confirm reserve, not found in DB");
+      return;
+    }
     const historyEntry = {
       type: "confirm-reserve",
       timestamp: now,
@@ -766,23 +749,22 @@ export class Wallet {
         requestedAmount: reserve.requested_amount,
       }
     };
-    if (!reserve) {
-      console.error("Unable to confirm reserve, not found in DB");
-      return;
-    }
     reserve.confirmed = true;
-    await Query(this.db)
-      .put("reserves", reserve)
-      .put("history", historyEntry)
-      .finish();
+    await this.q()
+              .put("reserves", reserve)
+              .put("history", historyEntry)
+              .finish();
 
     this.processReserve(reserve);
   }
 
 
   private async withdrawExecute(pc: PreCoin): Promise<Coin> {
-    let reserve = await Query(this.db)
-      .get("reserves", pc.reservePub);
+    let reserve = await this.q().get<ReserveRecord>("reserves", pc.reservePub);
+
+    if (!reserve) {
+      throw Error("db inconsistent");
+    }
 
     let wd: any = {};
     wd.denom_pub = pc.denomPub;
@@ -801,8 +783,8 @@ export class Wallet {
     }
     let r = JSON.parse(resp.responseText);
     let denomSig = await this.cryptoApi.rsaUnblind(r.ev_sig,
-      pc.blindingKey,
-      pc.denomPub);
+                                                   pc.blindingKey,
+                                                   pc.denomPub);
     let coin: Coin = {
       coinPub: pc.coinPub,
       coinPriv: pc.coinPriv,
@@ -825,11 +807,11 @@ export class Wallet {
         coinPub: coin.coinPub,
       }
     };
-    await Query(this.db)
-      .delete("precoins", coin.coinPub)
-      .add("coins", coin)
-      .add("history", historyEntry)
-      .finish();
+    await this.q()
+              .delete("precoins", coin.coinPub)
+              .add("coins", coin)
+              .add("history", historyEntry)
+              .finish();
     this.notifier.notify();
   }
 
@@ -837,13 +819,14 @@ export class Wallet {
   /**
    * Withdraw one coin of the given denomination from the given reserve.
    */
-  private async withdraw(denom: Denomination, reserve: Reserve): Promise<void> {
+  private async withdraw(denom: Denomination,
+                         reserve: ReserveRecord): Promise<void> {
     console.log("creating pre coin at", new Date());
     let preCoin = await this.cryptoApi
-      .createPreCoin(denom, reserve);
-    await Query(this.db)
-      .put("precoins", preCoin)
-      .finish();
+                            .createPreCoin(denom, reserve);
+    await this.q()
+              .put("precoins", preCoin)
+              .finish();
     await this.processPreCoin(preCoin);
   }
 
@@ -852,10 +835,10 @@ export class Wallet {
    * Withdraw coins from a reserve until it is empty.
    */
   private async depleteReserve(reserve: any,
-    exchange: IExchangeInfo): Promise<number> {
+                               exchange: IExchangeInfo): Promise<number> {
     let denomsAvailable: Denomination[] = copy(exchange.active_denoms);
     let denomsForWithdraw = getWithdrawDenomList(reserve.current_amount,
-      denomsAvailable);
+                                                 denomsAvailable);
 
     let ps = denomsForWithdraw.map((denom) => this.withdraw(denom, reserve));
     await Promise.all(ps);
@@ -868,11 +851,14 @@ export class Wallet {
    * by quering the reserve's exchange.
    */
   private async updateReserve(reservePub: string,
-    exchange: IExchangeInfo): Promise<Reserve> {
-    let reserve = await Query(this.db)
-      .get("reserves", reservePub);
+                              exchange: IExchangeInfo): Promise<ReserveRecord> {
+    let reserve = await this.q()
+                            .get<ReserveRecord>("reserves", reservePub);
+    if (!reserve) {
+      throw Error("reserve not in db");
+    }
     let reqUrl = URI("reserve/status").absoluteTo(exchange.baseUrl);
-    reqUrl.query({ 'reserve_pub': reservePub });
+    reqUrl.query({'reserve_pub': reservePub});
     let resp = await this.http.get(reqUrl);
     if (resp.status != 200) {
       throw Error();
@@ -895,9 +881,9 @@ export class Wallet {
         newAmount
       }
     };
-    await Query(this.db)
-      .put("reserves", reserve)
-      .finish();
+    await this.q()
+              .put("reserves", reserve)
+              .finish();
     return reserve;
   }
 
@@ -922,18 +908,18 @@ export class Wallet {
   }
 
   async getReserveCreationInfo(baseUrl: string,
-    amount: AmountJson): Promise<ReserveCreationInfo> {
+                               amount: AmountJson): Promise<ReserveCreationInfo> {
     let exchangeInfo = await this.updateExchangeFromUrl(baseUrl);
 
     let selectedDenoms = getWithdrawDenomList(amount,
-      exchangeInfo.active_denoms);
+                                              exchangeInfo.active_denoms);
     let acc = Amounts.getZero(amount.currency);
     for (let d of selectedDenoms) {
       acc = Amounts.add(acc, d.fee_withdraw).amount;
     }
     let actualCoinCost = selectedDenoms
       .map((d: Denomination) => Amounts.add(d.value,
-        d.fee_withdraw).amount)
+                                            d.fee_withdraw).amount)
       .reduce((a, b) => Amounts.add(a, b).amount);
 
     let wireInfo = await this.getWireInfo(baseUrl);
@@ -966,17 +952,18 @@ export class Wallet {
   }
 
   private async suspendCoins(exchangeInfo: IExchangeInfo): Promise<void> {
-    let suspendedCoins = await Query(this.db)
-      .iter("coins",
-      { indexName: "exchangeBaseUrl", only: exchangeInfo.baseUrl })
-      .reduce((coin: Coin, suspendedCoins: Coin[]) => {
-        if (!exchangeInfo.active_denoms.find((c) => c.denom_pub == coin.denomPub)) {
-          return Array.prototype.concat(suspendedCoins, [coin]);
-        }
-        return Array.prototype.concat(suspendedCoins);
-      }, []);
+    let suspendedCoins = await (
+      this.q()
+          .iter("coins",
+                {indexName: "exchangeBaseUrl", only: exchangeInfo.baseUrl})
+          .reduce((coin: Coin, suspendedCoins: Coin[]) => {
+            if (!exchangeInfo.active_denoms.find((c) => c.denom_pub == coin.denomPub)) {
+              return Array.prototype.concat(suspendedCoins, [coin]);
+            }
+            return Array.prototype.concat(suspendedCoins);
+          }, []));
 
-    let q = Query(this.db);
+    let q = this.q();
     suspendedCoins.map((c) => {
       console.log("suspending coin", c);
       c.suspended = true;
@@ -987,13 +974,13 @@ export class Wallet {
 
 
   private async updateExchangeFromJson(baseUrl: string,
-    exchangeKeysJson: KeysJson): Promise<IExchangeInfo> {
+                                       exchangeKeysJson: KeysJson): Promise<IExchangeInfo> {
     const updateTimeSec = getTalerStampSec(exchangeKeysJson.list_issue_date);
     if (updateTimeSec === null) {
       throw Error("invalid update time");
     }
 
-    let r = await Query(this.db).get("exchanges", baseUrl);
+    let r = await this.q().get<IExchangeInfo>("exchanges", baseUrl);
 
     let exchangeInfo: IExchangeInfo;
 
@@ -1016,19 +1003,19 @@ export class Wallet {
     }
 
     let updatedExchangeInfo = await this.updateExchangeInfo(exchangeInfo,
-      exchangeKeysJson);
+                                                            exchangeKeysJson);
     await this.suspendCoins(updatedExchangeInfo);
 
-    await Query(this.db)
-      .put("exchanges", updatedExchangeInfo)
-      .finish();
+    await this.q()
+              .put("exchanges", updatedExchangeInfo)
+              .finish();
 
     return updatedExchangeInfo;
   }
 
 
   private async updateExchangeInfo(exchangeInfo: IExchangeInfo,
-    newKeys: KeysJson): Promise<IExchangeInfo> {
+                                   newKeys: KeysJson): Promise<IExchangeInfo> {
     if (exchangeInfo.masterPublicKey != newKeys.master_public_key) {
       throw Error("public keys do not match");
     }
@@ -1064,15 +1051,15 @@ export class Wallet {
       return true;
     });
 
-    let ps = denomsToCheck.map(async (denom) => {
+    let ps = denomsToCheck.map(async(denom) => {
       let valid = await this.cryptoApi
-        .isValidDenom(denom,
-        exchangeInfo.masterPublicKey);
+                            .isValidDenom(denom,
+                                          exchangeInfo.masterPublicKey);
       if (!valid) {
         console.error("invalid denomination",
-          denom,
-          "with key",
-          exchangeInfo.masterPublicKey);
+                      denom,
+                      "with key",
+                      exchangeInfo.masterPublicKey);
         // FIXME: report to auditors
       }
       exchangeInfo.active_denoms.push(denom);
@@ -1099,15 +1086,58 @@ export class Wallet {
         acc = Amounts.getZero(c.currentAmount.currency);
       }
       byCurrency[c.currentAmount.currency] = Amounts.add(c.currentAmount,
-        acc).amount;
+                                                         acc).amount;
       return byCurrency;
     }
 
-    let byCurrency = await Query(this.db)
-      .iter("coins")
-      .reduce(collectBalances, {});
+    let byCurrency = await (
+      this.q()
+          .iter("coins")
+          .reduce(collectBalances, {}));
+
+    return {balances: byCurrency};
+  }
+
+
+  async refresh(oldCoinPub: string): Promise<void> {
+    // FIXME: this is not running in a transaction.
+
+    let coin = await this.q().get<Coin>("coins", oldCoinPub);
+
+    if (!coin) {
+      console.error("coin not found");
+      return;
+    }
+
+    let exchange = await this.q().get<IExchangeInfo>("exchanges",
+                                                     coin.exchangeBaseUrl);
+    if (!exchange) {
+      throw Error("db inconsistent");
+    }
+
+    let oldDenom = exchange.all_denoms.find((d) => d.denom_pub == coin!.denomPub);
+
+    if (!oldDenom) {
+      throw Error("db inconsistent");
+    }
+
+    let availableDenoms: Denomination[] = exchange.active_denoms;
+
+    let newCoinDenoms = getWithdrawDenomList(coin.currentAmount,
+                                             availableDenoms);
+
+    console.log("refreshing into", newCoinDenoms);
+
+
+    let refreshSession: RefreshSession = await (
+      this.cryptoApi.createWithdrawSession(3,
+                                           coin,
+                                           newCoinDenoms,
+                                           coin.currentAmount,
+                                           oldDenom.fee_refresh));
+
+    // FIXME: implement rest
 
-    return { balances: byCurrency };
   }
 
 
@@ -1120,40 +1150,40 @@ export class Wallet {
       return acc;
     }
 
-    let history = await
-      Query(this.db)
-        .iter("history", { indexName: "timestamp" })
-        .reduce(collect, []);
+    let history = await (
+      this.q()
+          .iter("history", {indexName: "timestamp"})
+          .reduce(collect, []));
 
-    return { history };
+    return {history};
   }
 
   async getExchanges(): Promise<IExchangeInfo[]> {
-    return Query(this.db)
-      .iter<IExchangeInfo>("exchanges")
-      .flatMap((e) => [e])
-      .toArray();
+    return this.q()
+               .iter<IExchangeInfo>("exchanges")
+               .flatMap((e) => [e])
+               .toArray();
   }
 
-  async getReserves(exchangeBaseUrl: string): Promise<Reserve[]> {
-    return Query(this.db)
-      .iter<Reserve>("reserves")
-      .filter((r: Reserve) => r.exchange_base_url === exchangeBaseUrl)
-      .toArray();
+  async getReserves(exchangeBaseUrl: string): Promise<ReserveRecord[]> {
+    return this.q()
+               .iter<ReserveRecord>("reserves")
+               .filter((r: ReserveRecord) => r.exchange_base_url === exchangeBaseUrl)
+               .toArray();
   }
 
   async getCoins(exchangeBaseUrl: string): Promise<Coin[]> {
-    return Query(this.db)
-      .iter<Coin>("coins")
-      .filter((c: Coin) => c.exchangeBaseUrl === exchangeBaseUrl)
-      .toArray();
+    return this.q()
+               .iter<Coin>("coins")
+               .filter((c: Coin) => c.exchangeBaseUrl === exchangeBaseUrl)
+               .toArray();
   }
 
   async getPreCoins(exchangeBaseUrl: string): Promise<PreCoin[]> {
-    return Query(this.db)
-      .iter<PreCoin>("precoins")
-      .filter((c: PreCoin) => c.exchangeBaseUrl === exchangeBaseUrl)
-      .toArray();
+    return this.q()
+               .iter<PreCoin>("precoins")
+               .filter((c: PreCoin) => c.exchangeBaseUrl === exchangeBaseUrl)
+               .toArray();
   }
 
 
@@ -1167,12 +1197,16 @@ export class Wallet {
   async checkRepurchase(contract: Contract): Promise<CheckRepurchaseResult> {
     if (!contract.repurchase_correlation_id) {
       console.log("no repurchase: no correlation id");
-      return { isRepurchase: false };
+      return {isRepurchase: false};
     }
-    let result: Transaction = await Query(this.db)
-      .getIndexed("transactions",
-      "repurchase",
-      [contract.merchant_pub, contract.repurchase_correlation_id]);
+    let result: Transaction = await (
+      this.q()
+          .getIndexed("transactions",
+                      "repurchase",
+                      [
+                        contract.merchant_pub,
+                        contract.repurchase_correlation_id
+                      ]));
 
     if (result) {
       console.assert(result.contract.repurchase_correlation_id == contract.repurchase_correlation_id);
@@ -1182,7 +1216,7 @@ export class Wallet {
         existingFulfillmentUrl: result.contract.fulfillment_url,
       };
     } else {
-      return { isRepurchase: false };
+      return {isRepurchase: false};
     }
   }
 }
diff --git a/lib/wallet/wxApi.ts b/lib/wallet/wxApi.ts
index 549ce0a5a..12d11a387 100644
--- a/lib/wallet/wxApi.ts
+++ b/lib/wallet/wxApi.ts
@@ -20,7 +20,7 @@ import {
   PreCoin,
   ReserveCreationInfo,
   IExchangeInfo,
-  Reserve
+  ReserveRecord
 } from "./types";
 
 /**
@@ -58,7 +58,7 @@ export async function getExchanges(): Promise<IExchangeInfo[]> {
   return await callBackend("get-exchanges");
 }
 
-export async function getReserves(exchangeBaseUrl: string): Promise<Reserve[]> {
+export async function getReserves(exchangeBaseUrl: string): Promise<ReserveRecord[]> {
   return await callBackend("get-reserves", { exchangeBaseUrl });
 }
 
diff --git a/pages/tree.tsx b/pages/tree.tsx
index b1c22b9f8..ba5f787b4 100644
--- a/pages/tree.tsx
+++ b/pages/tree.tsx
@@ -23,18 +23,18 @@
 /// <reference path="../lib/decl/preact.d.ts" />
 
 import { IExchangeInfo } from "../lib/wallet/types";
-import { Reserve, Coin, PreCoin, Denomination } from "../lib/wallet/types";
+import { ReserveRecord, Coin, PreCoin, Denomination } from "../lib/wallet/types";
 import { ImplicitStateComponent, StateHolder } from "../lib/components";
 import { getReserves, getExchanges, getCoins, getPreCoins } from "../lib/wallet/wxApi";
 import { prettyAmount, abbrev } from "../lib/wallet/renderHtml";
 
 interface ReserveViewProps {
-  reserve: Reserve;
+  reserve: ReserveRecord;
 }
 
 class ReserveView extends preact.Component<ReserveViewProps, void> {
   render(): JSX.Element {
-    let r: Reserve = this.props.reserve;
+    let r: ReserveRecord = this.props.reserve;
     return (
       <div className="tree-item">
         <ul>
@@ -248,7 +248,7 @@ class DenominationList extends ImplicitStateComponent<DenominationListProps> {
 }
 
 class ReserveList extends ImplicitStateComponent<ReserveListProps> {
-  reserves = this.makeState<Reserve[] | null>(null);
+  reserves = this.makeState<ReserveRecord[] | null>(null);
   expanded = this.makeState<boolean>(false);
 
   constructor(props: ReserveListProps) {