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bitcoin/src/base58.h

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1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2011 The Bitcoin Developers
3// Distributed under the MIT/X11 software license, see the accompanying
4// file license.txt or http://www.opensource.org/licenses/mit-license.php.
5
6
7//
8// Why base-58 instead of standard base-64 encoding?
9// - Don't want 0OIl characters that look the same in some fonts and
10// could be used to create visually identical looking account numbers.
11// - A string with non-alphanumeric characters is not as easily accepted as an account number.
12// - E-mail usually won't line-break if there's no punctuation to break at.
13// - Doubleclicking selects the whole number as one word if it's all alphanumeric.
14//
15#ifndef BITCOIN_BASE58_H
16#define BITCOIN_BASE58_H
17
18#include <string>
19#include <vector>
20#include "bignum.h"
21#include "key.h"
22
23static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
24
25// Encode a byte sequence as a base58-encoded string
26inline std::string EncodeBase58(const unsigned char* pbegin, const unsigned char* pend)
27{
28 CAutoBN_CTX pctx;
29 CBigNum bn58 = 58;
30 CBigNum bn0 = 0;
31
32 // Convert big endian data to little endian
33 // Extra zero at the end make sure bignum will interpret as a positive number
34 std::vector<unsigned char> vchTmp(pend-pbegin+1, 0);
35 reverse_copy(pbegin, pend, vchTmp.begin());
36
37 // Convert little endian data to bignum
38 CBigNum bn;
39 bn.setvch(vchTmp);
40
41 // Convert bignum to std::string
42 std::string str;
43 // Expected size increase from base58 conversion is approximately 137%
44 // use 138% to be safe
45 str.reserve((pend - pbegin) * 138 / 100 + 1);
46 CBigNum dv;
47 CBigNum rem;
48 while (bn > bn0)
49 {
50 if (!BN_div(&dv, &rem, &bn, &bn58, pctx))
51 throw bignum_error("EncodeBase58 : BN_div failed");
52 bn = dv;
53 unsigned int c = rem.getulong();
54 str += pszBase58[c];
55 }
56
57 // Leading zeroes encoded as base58 zeros
58 for (const unsigned char* p = pbegin; p < pend && *p == 0; p++)
59 str += pszBase58[0];
60
61 // Convert little endian std::string to big endian
62 reverse(str.begin(), str.end());
63 return str;
64}
65
66// Encode a byte vector as a base58-encoded string
67inline std::string EncodeBase58(const std::vector<unsigned char>& vch)
68{
69 return EncodeBase58(&vch[0], &vch[0] + vch.size());
70}
71
72// Decode a base58-encoded string psz into byte vector vchRet
73// returns true if decoding is succesful
74inline bool DecodeBase58(const char* psz, std::vector<unsigned char>& vchRet)
75{
76 CAutoBN_CTX pctx;
77 vchRet.clear();
78 CBigNum bn58 = 58;
79 CBigNum bn = 0;
80 CBigNum bnChar;
81 while (isspace(*psz))
82 psz++;
83
84 // Convert big endian string to bignum
85 for (const char* p = psz; *p; p++)
86 {
87 const char* p1 = strchr(pszBase58, *p);
88 if (p1 == NULL)
89 {
90 while (isspace(*p))
91 p++;
92 if (*p != '\0')
93 return false;
94 break;
95 }
96 bnChar.setulong(p1 - pszBase58);
97 if (!BN_mul(&bn, &bn, &bn58, pctx))
98 throw bignum_error("DecodeBase58 : BN_mul failed");
99 bn += bnChar;
100 }
101
102 // Get bignum as little endian data
103 std::vector<unsigned char> vchTmp = bn.getvch();
104
105 // Trim off sign byte if present
106 if (vchTmp.size() >= 2 && vchTmp.end()[-1] == 0 && vchTmp.end()[-2] >= 0x80)
107 vchTmp.erase(vchTmp.end()-1);
108
109 // Restore leading zeros
110 int nLeadingZeros = 0;
111 for (const char* p = psz; *p == pszBase58[0]; p++)
112 nLeadingZeros++;
113 vchRet.assign(nLeadingZeros + vchTmp.size(), 0);
114
115 // Convert little endian data to big endian
116 reverse_copy(vchTmp.begin(), vchTmp.end(), vchRet.end() - vchTmp.size());
117 return true;
118}
119
120// Decode a base58-encoded string str into byte vector vchRet
121// returns true if decoding is succesful
122inline bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet)
123{
124 return DecodeBase58(str.c_str(), vchRet);
125}
126
127
128
129
130// Encode a byte vector to a base58-encoded string, including checksum
131inline std::string EncodeBase58Check(const std::vector<unsigned char>& vchIn)
132{
133 // add 4-byte hash check to the end
134 std::vector<unsigned char> vch(vchIn);
135 uint256 hash = Hash(vch.begin(), vch.end());
136 vch.insert(vch.end(), (unsigned char*)&hash, (unsigned char*)&hash + 4);
137 return EncodeBase58(vch);
138}
139
140// Decode a base58-encoded string psz that includes a checksum, into byte vector vchRet
141// returns true if decoding is succesful
142inline bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet)
143{
144 if (!DecodeBase58(psz, vchRet))
145 return false;
146 if (vchRet.size() < 4)
147 {
148 vchRet.clear();
149 return false;
150 }
151 uint256 hash = Hash(vchRet.begin(), vchRet.end()-4);
152 if (memcmp(&hash, &vchRet.end()[-4], 4) != 0)
153 {
154 vchRet.clear();
155 return false;
156 }
157 vchRet.resize(vchRet.size()-4);
158 return true;
159}
160
161// Decode a base58-encoded string str that includes a checksum, into byte vector vchRet
162// returns true if decoding is succesful
163inline bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet)
164{
165 return DecodeBase58Check(str.c_str(), vchRet);
166}
167
168
169
170
171
172// Base class for all base58-encoded data
173class CBase58Data
174{
175protected:
176 // the version byte
177 unsigned char nVersion;
178
179 // the actually encoded data
180 std::vector<unsigned char> vchData;
181
182 CBase58Data()
183 {
184 nVersion = 0;
185 vchData.clear();
186 }
187
188 ~CBase58Data()
189 {
190 // zero the memory, as it may contain sensitive data
191 if (!vchData.empty())
192 memset(&vchData[0], 0, vchData.size());
193 }
194
195 void SetData(int nVersionIn, const void* pdata, size_t nSize)
196 {
197 nVersion = nVersionIn;
198 vchData.resize(nSize);
199 if (!vchData.empty())
200 memcpy(&vchData[0], pdata, nSize);
201 }
202
203 void SetData(int nVersionIn, const unsigned char *pbegin, const unsigned char *pend)
204 {
205 SetData(nVersionIn, (void*)pbegin, pend - pbegin);
206 }
207
208public:
209 bool SetString(const char* psz)
210 {
211 std::vector<unsigned char> vchTemp;
212 DecodeBase58Check(psz, vchTemp);
213 if (vchTemp.empty())
214 {
215 vchData.clear();
216 nVersion = 0;
217 return false;
218 }
219 nVersion = vchTemp[0];
220 vchData.resize(vchTemp.size() - 1);
221 if (!vchData.empty())
222 memcpy(&vchData[0], &vchTemp[1], vchData.size());
223 memset(&vchTemp[0], 0, vchTemp.size());
224 return true;
225 }
226
227 bool SetString(const std::string& str)
228 {
229 return SetString(str.c_str());
230 }
231
232 std::string ToString() const
233 {
234 std::vector<unsigned char> vch(1, nVersion);
235 vch.insert(vch.end(), vchData.begin(), vchData.end());
236 return EncodeBase58Check(vch);
237 }
238
239 int CompareTo(const CBase58Data& b58) const
240 {
241 if (nVersion < b58.nVersion) return -1;
242 if (nVersion > b58.nVersion) return 1;
243 if (vchData < b58.vchData) return -1;
244 if (vchData > b58.vchData) return 1;
245 return 0;
246 }
247
248 bool operator==(const CBase58Data& b58) const { return CompareTo(b58) == 0; }
249 bool operator<=(const CBase58Data& b58) const { return CompareTo(b58) <= 0; }
250 bool operator>=(const CBase58Data& b58) const { return CompareTo(b58) >= 0; }
251 bool operator< (const CBase58Data& b58) const { return CompareTo(b58) < 0; }
252 bool operator> (const CBase58Data& b58) const { return CompareTo(b58) > 0; }
253};
254
255// base58-encoded bitcoin addresses
256// Addresses have version 0
257// The data vector contains RIPEMD160(SHA256(pubkey)), where pubkey is the serialized public key
258class CBitcoinAddress : public CBase58Data
259{
260public:
261 bool SetHash160(const uint160& hash160)
262 {
263 SetData(0, &hash160, 20);
264 return true;
265 }
266
267 bool SetPubKey(const std::vector<unsigned char>& vchPubKey)
268 {
269 return SetHash160(Hash160(vchPubKey));
270 }
271
272 bool IsValid() const
273 {
274 int nExpectedSize = 20;
275 switch(nVersion)
276 {
277 case 0:
278 break;
279
280 default:
281 return false;
282 }
283 return vchData.size() == nExpectedSize;
284 }
285
286 CBitcoinAddress()
287 {
288 }
289
290 CBitcoinAddress(uint160 hash160In)
291 {
292 SetHash160(hash160In);
293 }
294
295 CBitcoinAddress(const std::vector<unsigned char>& vchPubKey)
296 {
297 SetPubKey(vchPubKey);
298 }
299
300 CBitcoinAddress(const std::string& strAddress)
301 {
302 SetString(strAddress);
303 }
304
305 CBitcoinAddress(const char* pszAddress)
306 {
307 SetString(pszAddress);
308 }
309
310 uint160 GetHash160() const
311 {
312 assert(vchData.size() == 20);
313 uint160 hash160;
314 memcpy(&hash160, &vchData[0], 20);
315 return hash160;
316 }
317};
318
319/** A base58-encoded secret key */
320class CBitcoinSecret : public CBase58Data
321{
322public:
323 void SetSecret(const CSecret& vchSecret)
324 {
325 assert(vchSecret.size() == 32);
326 SetData(128, &vchSecret[0], vchSecret.size());
327 }
328
329 CSecret GetSecret()
330 {
331 CSecret vchSecret;
332 vchSecret.resize(32);
333 memcpy(&vchSecret[0], &vchData[0], 32);
334 return vchSecret;
335 }
336
337 CBitcoinSecret(const CSecret& vchSecret)
338 {
339 SetSecret(vchSecret);
340 }
341
342 CBitcoinSecret()
343 {
344 }
345};
346
347#endif