diff options
Diffstat (limited to 'libtomcrypt/src/misc/base64/base64_decode.c')
| -rw-r--r-- | libtomcrypt/src/misc/base64/base64_decode.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/libtomcrypt/src/misc/base64/base64_decode.c b/libtomcrypt/src/misc/base64/base64_decode.c new file mode 100644 index 0000000..551add1 --- /dev/null +++ b/libtomcrypt/src/misc/base64/base64_decode.c @@ -0,0 +1,104 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org + */ +#include "tomcrypt.h" + +/** + @file base64_decode.c + Compliant base64 code donated by Wayne Scott (wscott@bitmover.com) +*/ + + +#ifdef BASE64 + +static const unsigned char map[256] = { +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, +255, 254, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, + 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, + 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255, +255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, + 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, + 49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, +255, 255, 255, 255 }; + +/** + base64 decode a block of memory + @param in The base64 data to decode + @param inlen The length of the base64 data + @param out [out] The destination of the binary decoded data + @param outlen [in/out] The max size and resulting size of the decoded data + @return CRYPT_OK if successful +*/ +int base64_decode(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen) +{ + unsigned long t, x, y, z; + unsigned char c; + int g; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + + g = 3; + for (x = y = z = t = 0; x < inlen; x++) { + c = map[in[x]&0xFF]; + if (c == 255) continue; + /* the final = symbols are read and used to trim the remaining bytes */ + if (c == 254) { + c = 0; + /* prevent g < 0 which would potentially allow an overflow later */ + if (--g < 0) { + return CRYPT_INVALID_PACKET; + } + } else if (g != 3) { + /* we only allow = to be at the end */ + return CRYPT_INVALID_PACKET; + } + + t = (t<<6)|c; + + if (++y == 4) { + if (z + g > *outlen) { + return CRYPT_BUFFER_OVERFLOW; + } + out[z++] = (unsigned char)((t>>16)&255); + if (g > 1) out[z++] = (unsigned char)((t>>8)&255); + if (g > 2) out[z++] = (unsigned char)(t&255); + y = t = 0; + } + } + if (y != 0) { + return CRYPT_INVALID_PACKET; + } + *outlen = z; + return CRYPT_OK; +} + +#endif + + +/* $Source: /cvs/libtom/libtomcrypt/src/misc/base64/base64_decode.c,v $ */ +/* $Revision: 1.3 $ */ +/* $Date: 2005/05/05 14:35:59 $ */ |