/*++ /* NAME /* base32_code 3 /* SUMMARY /* encode/decode data, base 32 style /* SYNOPSIS /* #include <base32_code.h> /* /* VSTRING *base32_encode(result, in, len) /* VSTRING *result; /* const char *in; /* ssize_t len; /* /* VSTRING *base32_decode(result, in, len) /* VSTRING *result; /* const char *in; /* ssize_t len; /* DESCRIPTION /* base32_encode() takes a block of len bytes and encodes it as one /* null-terminated string. The result value is the result argument. /* /* base32_decode() performs the opposite transformation. The result /* value is the result argument. The result is null terminated, whether /* or not that makes sense. /* DIAGNOSTICS /* base32_decode() returns a null pointer when the input contains /* characters not in the base 32 alphabet. /* SEE ALSO /* RFC 4648; padding is strictly enforced /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include "sys_defs.h" #include <ctype.h> #include <string.h> #include <limits.h> #ifndef UCHAR_MAX #define UCHAR_MAX 0xff #endif /* Utility library. */ #include <msg.h> #include <mymalloc.h> #include <vstring.h> #include <base32_code.h> /* Application-specific. */ static unsigned char to_b32[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"; #define UNSIG_CHAR_PTR(x) ((unsigned char *)(x)) /* base32_encode - raw data to encoded */ VSTRING *base32_encode(VSTRING *result, const char *in, ssize_t len) { const unsigned char *cp; ssize_t count; static int pad_count[] = {0, 6, 4, 3, 1}; /* * Encode 5 -> 8. */ VSTRING_RESET(result); for (cp = UNSIG_CHAR_PTR(in), count = len; count > 0; count -= 5, cp += 5) { VSTRING_ADDCH(result, to_b32[cp[0] >> 3]); if (count < 2) { VSTRING_ADDCH(result, to_b32[(cp[0] & 0x7) << 2]); break; } VSTRING_ADDCH(result, to_b32[(cp[0] & 0x7) << 2 | cp[1] >> 6]); VSTRING_ADDCH(result, to_b32[(cp[1] & 0x3f) >> 1]); if (count < 3) { VSTRING_ADDCH(result, to_b32[(cp[1] & 0x1) << 4]); break; } VSTRING_ADDCH(result, to_b32[(cp[1] & 0x1) << 4 | cp[2] >> 4]); if (count < 4) { VSTRING_ADDCH(result, to_b32[(cp[2] & 0xf) << 1]); break; } VSTRING_ADDCH(result, to_b32[(cp[2] & 0xf) << 1 | cp[3] >> 7]); VSTRING_ADDCH(result, to_b32[(cp[3] & 0x7f) >> 2]); if (count < 5) { VSTRING_ADDCH(result, to_b32[(cp[3] & 0x3) << 3]); break; } VSTRING_ADDCH(result, to_b32[(cp[3] & 0x3) << 3 | cp[4] >> 5]); VSTRING_ADDCH(result, to_b32[cp[4] & 0x1f]); } if (count > 0) vstring_strncat(result, "======", pad_count[count]); VSTRING_TERMINATE(result); return (result); } /* base32_decode - encoded data to raw */ VSTRING *base32_decode(VSTRING *result, const char *in, ssize_t len) { static unsigned char *un_b32 = 0; const unsigned char *cp; ssize_t count; unsigned int ch0; unsigned int ch1; unsigned int ch2; unsigned int ch3; unsigned int ch4; unsigned int ch5; unsigned int ch6; unsigned int ch7; #define CHARS_PER_BYTE (UCHAR_MAX + 1) #define INVALID 0xff #if 1 #define ENFORCE_LENGTH(x) (x) #define ENFORCE_PADDING(x) (x) #define ENFORCE_NULL_BITS(x) (x) #else #define ENFORCE_LENGTH(x) (1) #define ENFORCE_PADDING(x) (1) #define ENFORCE_NULL_BITS(x) (1) #endif /* * Sanity check. */ if (ENFORCE_LENGTH(len % 8)) return (0); /* * Once: initialize the decoding lookup table on the fly. */ if (un_b32 == 0) { un_b32 = (unsigned char *) mymalloc(CHARS_PER_BYTE); memset(un_b32, INVALID, CHARS_PER_BYTE); for (cp = to_b32; cp < to_b32 + sizeof(to_b32) - 1; cp++) un_b32[*cp] = cp - to_b32; } /* * Decode 8 -> 5. */ VSTRING_RESET(result); for (cp = UNSIG_CHAR_PTR(in), count = 0; count < len; count += 8) { if ((ch0 = un_b32[*cp++]) == INVALID || (ch1 = un_b32[*cp++]) == INVALID) return (0); VSTRING_ADDCH(result, ch0 << 3 | ch1 >> 2); if ((ch2 = *cp++) == '=' && ENFORCE_PADDING(strcmp((char *) cp, "=====") == 0) && ENFORCE_NULL_BITS((ch1 & 0x3) == 0)) break; if ((ch2 = un_b32[ch2]) == INVALID) return (0); if ((ch3 = un_b32[*cp++]) == INVALID) return (0); VSTRING_ADDCH(result, ch1 << 6 | ch2 << 1 | ch3 >> 4); if ((ch4 = *cp++) == '=' && ENFORCE_PADDING(strcmp((char *) cp, "===") == 0) && ENFORCE_NULL_BITS((ch3 & 0xf) == 0)) break; if ((ch4 = un_b32[ch4]) == INVALID) return (0); VSTRING_ADDCH(result, ch3 << 4 | ch4 >> 1); if ((ch5 = *cp++) == '=' && ENFORCE_PADDING(strcmp((char *) cp, "==") == 0) && ENFORCE_NULL_BITS((ch4 & 0x1) == 0)) break; if ((ch5 = un_b32[ch5]) == INVALID) return (0); if ((ch6 = un_b32[*cp++]) == INVALID) return (0); VSTRING_ADDCH(result, ch4 << 7 | ch5 << 2 | ch6 >> 3); if ((ch7 = *cp++) == '=' && ENFORCE_NULL_BITS((ch6 & 0x7) == 0)) break; if ((ch7 = un_b32[ch7]) == INVALID) return (0); VSTRING_ADDCH(result, ch6 << 5 | ch7); } VSTRING_TERMINATE(result); return (result); } #ifdef TEST /* * Proof-of-concept test program: convert to base 32 and back. */ #define STR(x) vstring_str(x) #define LEN(x) VSTRING_LEN(x) int main(int unused_argc, char **unused_argv) { VSTRING *b1 = vstring_alloc(1); VSTRING *b2 = vstring_alloc(1); VSTRING *test = vstring_alloc(1); int i, j; /* * Test all byte values (except null) on all byte positions. */ for (j = 0; j < 256; j++) for (i = 1; i < 256; i++) VSTRING_ADDCH(test, i); VSTRING_TERMINATE(test); #define DECODE(b,x,l) { \ if (base32_decode((b),(x),(l)) == 0) \ msg_panic("bad base32: %s", (x)); \ } #define VERIFY(b,t,l) { \ if (memcmp((b), (t), (l)) != 0) \ msg_panic("bad test: %s", (b)); \ } /* * Test all padding variants. */ for (i = 1; i <= 8; i++) { base32_encode(b1, STR(test), LEN(test)); DECODE(b2, STR(b1), LEN(b1)); VERIFY(STR(b2), STR(test), LEN(test)); base32_encode(b1, STR(test), LEN(test)); base32_encode(b2, STR(b1), LEN(b1)); base32_encode(b1, STR(b2), LEN(b2)); DECODE(b2, STR(b1), LEN(b1)); DECODE(b1, STR(b2), LEN(b2)); DECODE(b2, STR(b1), LEN(b1)); VERIFY(STR(b2), STR(test), LEN(test)); base32_encode(b1, STR(test), LEN(test)); base32_encode(b2, STR(b1), LEN(b1)); base32_encode(b1, STR(b2), LEN(b2)); base32_encode(b2, STR(b1), LEN(b1)); base32_encode(b1, STR(b2), LEN(b2)); DECODE(b2, STR(b1), LEN(b1)); DECODE(b1, STR(b2), LEN(b2)); DECODE(b2, STR(b1), LEN(b1)); DECODE(b1, STR(b2), LEN(b2)); DECODE(b2, STR(b1), LEN(b1)); VERIFY(STR(b2), STR(test), LEN(test)); vstring_truncate(test, LEN(test) - 1); } vstring_free(test); vstring_free(b1); vstring_free(b2); return (0); } #endif