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Fix base32 implementation; make base32 implementation follow standard; add more tests for base32

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svn:r1574
This commit is contained in:
Nick Mathewson 2004-04-08 20:56:33 +00:00
parent d237692396
commit aa7cfd93e5
4 changed files with 16 additions and 9 deletions
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6
doc/rend-spec.txt
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@ -183,10 +183,8 @@ Tor Rendezvous Spec
1. Let H = H(PK). 1. Let H = H(PK).
2. Let H' = the first 80 bits of H, considering each octet from 2. Let H' = the first 80 bits of H, considering each octet from
most significant bit to least significant bit. most significant bit to least significant bit.
2. Generate a 16-character encoding of H', taking H' 5 bits at 2. Generate a 16-character encoding of H', using base32 as defined
a time, and mapping each 5-bit value to a character as follows: in RFC 3548.
0..25 map to the characters 'a'...'z', respectively.
26..31 map to the characters '0'...'5', respectively.
(We only use 80 bits instead of the 160 bits from SHA1 because we don't (We only use 80 bits instead of the 160 bits from SHA1 because we don't
need to worry about man-in-the-middle attacks, and because it will make need to worry about man-in-the-middle attacks, and because it will make

9
src/common/crypto.c
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@ -1188,6 +1188,9 @@ base64_decode(char *dest, int destlen, const char *src, int srclen)
return ret; return ret;
} }
/* Implement base32 encoding as in rfc3548. Limitation: Requires that
* srclen is a multiple of 5.
*/
int int
base32_encode(char *dest, int destlen, const char *src, int srclen) base32_encode(char *dest, int destlen, const char *src, int srclen)
{ {
@ -1197,14 +1200,14 @@ base32_encode(char *dest, int destlen, const char *src, int srclen)
if ((nbits%5) != 0) if ((nbits%5) != 0)
/* We need an even multiple of 5 bits. */ /* We need an even multiple of 5 bits. */
return -1; return -1;
if ((nbits/5)+1 < destlen) if ((nbits/5)+1 > destlen)
/* Not enough space. */ /* Not enough space. */
return -1; return -1;
for (i=0,bit=0; bit < nbits; ++i, bit+=5) { for (i=0,bit=0; bit < nbits; ++i, bit+=5) {
/* set v to the 16-bit value starting at src[bits/8], 0-padded. */ /* set v to the 16-bit value starting at src[bits/8], 0-padded. */
v = ((unsigned char)src[bit/8]) << 8; v = ((uint8_t)src[bit/8]) << 8;
if (bit+5<nbits) v += src[(bit/8)+1]; if (bit+5<nbits) v += (uint8_t)src[(bit/8)+1];
/* set u to the 5-bit value at the bit'th bit of src. */ /* set u to the 5-bit value at the bit'th bit of src. */
u = (v >> (11-(bit%8))) & 0x1F; u = (v >> (11-(bit%8))) & 0x1F;
dest[i] = BASE32_CHARS[u]; dest[i] = BASE32_CHARS[u];

2
src/common/crypto.h
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@ -78,7 +78,7 @@ int crypto_pk_check_fingerprint_syntax(const char *s);
int base64_encode(char *dest, int destlen, const char *src, int srclen); int base64_encode(char *dest, int destlen, const char *src, int srclen);
int base64_decode(char *dest, int destlen, const char *src, int srclen); int base64_decode(char *dest, int destlen, const char *src, int srclen);
#define BASE32_CHARS "abcdefghijklmnopqrstuvwxyz012345" #define BASE32_CHARS "abcdefghijklmnopqrstuvwxyz234567"
int base32_encode(char *dest, int destlen, const char *src, int srclen); int base32_encode(char *dest, int destlen, const char *src, int srclen);
/* Key negotiation */ /* Key negotiation */

8
src/or/test.c
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@ -446,7 +446,13 @@ test_crypto()
* By 5s: [00110 10101 10001 10110 10000 11100 10011 10011] * By 5s: [00110 10101 10001 10110 10000 11100 10011 10011]
*/ */
i = base32_encode(data2, 9, data1, 5); i = base32_encode(data2, 9, data1, 5);
test_streq(data2, "gvrwq2tt"); test_streq(data2, "gvrwq4tt");
strcpy(data1, "\xFF\xF5\x6D\x44\xAE\x0D\x5C\xC9\x62\xC4");
printf("-------\n");
i = base32_encode(data2, 30, data1, 10);
test_eq(i,0);
test_streq(data2, "772w2rfobvomsywe");
free(data1); free(data1);
free(data2); free(data2);