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base58.h

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+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2011 The Bitcoin Developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file license.txt or http://www.opensource.org/licenses/mit-license.php.
+
+
+//
+// Why base-58 instead of standard base-64 encoding?
+// - Don't want 0OIl characters that look the same in some fonts and
+//      could be used to create visually identical looking account numbers.
+// - A string with non-alphanumeric characters is not as easily accepted as an account number.
+// - E-mail usually won't line-break if there's no punctuation to break at.
+// - Doubleclicking selects the whole number as one word if it's all alphanumeric.
+//
+#ifndef BITCOIN_BASE58_H
+#define BITCOIN_BASE58_H
+
+#include <string>
+#include <algorithm>
+#include <vector>
+#include "bignum.h"
+#include "BitcoinUtil.h"
+
+static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
+
+
+inline std::string EncodeBase58(const unsigned char* pbegin, const unsigned char* pend)
+{
+    CAutoBN_CTX pctx;
+    CBigNum bn58 = 58;
+    CBigNum bn0 = 0;
+
+    // Convert big endian data to little endian
+    // Extra zero at the end make sure bignum will interpret as a positive number
+    std::vector<unsigned char> vchTmp(pend-pbegin+1, 0);
+    std::reverse_copy(pbegin, pend, vchTmp.begin());
+
+    // Convert little endian data to bignum
+    CBigNum bn;
+    bn.setvch(vchTmp);
+
+    // Convert bignum to std::string
+    std::string str;
+    // Expected size increase from base58 conversion is approximately 137%
+    // use 138% to be safe
+    str.reserve((pend - pbegin) * 138 / 100 + 1);
+    CBigNum dv;
+    CBigNum rem;
+    while (bn > bn0)
+    {
+        if (!BN_div(&dv, &rem, &bn, &bn58, pctx))
+            throw bignum_error("EncodeBase58 : BN_div failed");
+        bn = dv;
+        unsigned int c = rem.getulong();
+        str += pszBase58[c];
+    }
+
+    // Leading zeroes encoded as base58 zeros
+    for (const unsigned char* p = pbegin; p < pend && *p == 0; p++)
+        str += pszBase58[0];
+
+    // Convert little endian std::string to big endian
+    reverse(str.begin(), str.end());
+    return str;
+}
+
+inline std::string EncodeBase58(const std::vector<unsigned char>& vch)
+{
+    return EncodeBase58(&vch[0], &vch[0] + vch.size());
+}
+
+inline bool DecodeBase58(const char* psz, std::vector<unsigned char>& vchRet)
+{
+    CAutoBN_CTX pctx;
+    vchRet.clear();
+    CBigNum bn58 = 58;
+    CBigNum bn = 0;
+    CBigNum bnChar;
+    while (isspace(*psz))
+        psz++;
+
+    // Convert big endian string to bignum
+    for (const char* p = psz; *p; p++)
+    {
+        const char* p1 = strchr(pszBase58, *p);
+        if (p1 == NULL)
+        {
+            while (isspace(*p))
+                p++;
+            if (*p != '\0')
+                return false;
+            break;
+        }
+        bnChar.setulong(p1 - pszBase58);
+        if (!BN_mul(&bn, &bn, &bn58, pctx))
+            throw bignum_error("DecodeBase58 : BN_mul failed");
+        bn += bnChar;
+    }
+
+    // Get bignum as little endian data
+    std::vector<unsigned char> vchTmp = bn.getvch();
+
+    // Trim off sign byte if present
+    if (vchTmp.size() >= 2 && vchTmp.end()[-1] == 0 && vchTmp.end()[-2] >= 0x80)
+        vchTmp.erase(vchTmp.end()-1);
+
+    // Restore leading zeros
+    int nLeadingZeros = 0;
+    for (const char* p = psz; *p == pszBase58[0]; p++)
+        nLeadingZeros++;
+    vchRet.assign(nLeadingZeros + vchTmp.size(), 0);
+
+    // Convert little endian data to big endian
+    std::reverse_copy(vchTmp.begin(), vchTmp.end(), vchRet.end() - vchTmp.size());
+    return true;
+}
+
+inline bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet)
+{
+    return DecodeBase58(str.c_str(), vchRet);
+}
+
+
+
+
+
+inline std::string EncodeBase58Check(const std::vector<unsigned char>& vchIn)
+{
+    // add 4-byte hash check to the end
+    std::vector<unsigned char> vch(vchIn);
+    uint256 hash = Hash(vch.begin(), vch.end());
+    vch.insert(vch.end(), (unsigned char*)&hash, (unsigned char*)&hash + 4);
+    return EncodeBase58(vch);
+}
+
+inline bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet)
+{
+    if (!DecodeBase58(psz, vchRet))
+        return false;
+    if (vchRet.size() < 4)
+    {
+        vchRet.clear();
+        return false;
+    }
+    uint256 hash = Hash(vchRet.begin(), vchRet.end()-4);
+    if (memcmp(&hash, &vchRet.end()[-4], 4) != 0)
+    {
+        vchRet.clear();
+        return false;
+    }
+    vchRet.resize(vchRet.size()-4);
+    return true;
+}
+
+inline bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet)
+{
+    return DecodeBase58Check(str.c_str(), vchRet);
+}
+
+
+
+
+
+
+class CBase58Data
+{
+protected:
+    unsigned char nVersion;
+    std::vector<unsigned char> vchData;
+
+    CBase58Data()
+    {
+        nVersion = 1;
+        vchData.clear();
+    }
+
+    ~CBase58Data()
+    {
+        if (!vchData.empty())
+            memset(&vchData[0], 0, vchData.size());
+    }
+
+    void SetData(int nVersionIn, const void* pdata, size_t nSize)
+    {
+        nVersion = nVersionIn;
+        vchData.resize(nSize);
+        if (!vchData.empty())
+            memcpy(&vchData[0], pdata, nSize);
+    }
+
+    void SetData(int nVersionIn, const unsigned char *pbegin, const unsigned char *pend)
+    {
+        SetData(nVersionIn, (void*)pbegin, pend - pbegin);
+    }
+
+public:
+    bool SetString(const char* psz)
+    {
+        std::vector<unsigned char> vchTemp;
+        DecodeBase58Check(psz, vchTemp);
+        if (vchTemp.empty())
+        {
+            vchData.clear();
+            nVersion = 0;
+            return false;
+        }
+        nVersion = vchTemp[0];
+        vchData.resize(vchTemp.size() - 1);
+        if (!vchData.empty())
+            memcpy(&vchData[0], &vchTemp[1], vchData.size());
+        memset(&vchTemp[0], 0, vchTemp.size());
+        return true;
+    }
+
+    bool SetString(const std::string& str)
+    {
+        return SetString(str.c_str());
+    }
+
+    std::string ToString() const
+    {
+        std::vector<unsigned char> vch(1, nVersion);
+        vch.insert(vch.end(), vchData.begin(), vchData.end());
+        return EncodeBase58Check(vch);
+    }
+
+    int CompareTo(const CBase58Data& b58) const
+    {
+        if (nVersion < b58.nVersion) return -1;
+        if (nVersion > b58.nVersion) return  1;
+        if (vchData < b58.vchData)   return -1;
+        if (vchData > b58.vchData)   return  1;
+        return 0;
+    }
+
+    bool operator==(const CBase58Data& b58) const { return CompareTo(b58) == 0; }
+    bool operator<=(const CBase58Data& b58) const { return CompareTo(b58) <= 0; }
+    bool operator>=(const CBase58Data& b58) const { return CompareTo(b58) >= 0; }
+    bool operator< (const CBase58Data& b58) const { return CompareTo(b58) <  0; }
+    bool operator> (const CBase58Data& b58) const { return CompareTo(b58) >  0; }
+};
+
+
+
+#endif