commit 27315de590da24fe55353332c29a3a4454ee7da2 Author: Daniel Pinto danielpinto52@gmail.com Date: Sat Jun 6 10:44:28 2020 +0100

Make curve25519_public_to_base64 output padding optional #7869 --- src/feature/hs/hs_descriptor.c | 7 ++++--- src/lib/crypt_ops/crypto_curve25519.h | 4 +++- src/lib/crypt_ops/crypto_format.c | 35 ++++++++++++++++++++++------------- src/lib/defs/x25519_sizes.h | 3 +++ src/test/test_crypto.c | 10 +++++----- 5 files changed, 37 insertions(+), 22 deletions(-)

diff --git a/src/feature/hs/hs_descriptor.c b/src/feature/hs/hs_descriptor.c index 50a46fb40f..30a36030d1 100644 --- a/src/feature/hs/hs_descriptor.c +++ b/src/feature/hs/hs_descriptor.c @@ -55,6 +55,7 @@ /* For unit tests.*/ #define HS_DESCRIPTOR_PRIVATE

+#include <stdbool.h> #include "core/or/or.h" #include "app/config/config.h" #include "trunnel/ed25519_cert.h" /* Trunnel interface. */ @@ -404,7 +405,7 @@ encode_enc_key(const hs_desc_intro_point_t *ip) tor_assert(ip);

/* Base64 encode the encryption key for the "enc-key" field. */ - curve25519_public_to_base64(key_b64, &ip->enc_key); + curve25519_public_to_base64(key_b64, &ip->enc_key, true); if (tor_cert_encode_ed22519(ip->enc_key_cert, &encoded_cert) < 0) { goto done; } @@ -430,7 +431,7 @@ encode_onion_key(const hs_desc_intro_point_t *ip) tor_assert(ip);

/* Base64 encode the encryption key for the "onion-key" field. */ - curve25519_public_to_base64(key_b64, &ip->onion_key); + curve25519_public_to_base64(key_b64, &ip->onion_key, true); tor_asprintf(&encoded, "%s ntor %s", str_ip_onion_key, key_b64);

return encoded; @@ -813,7 +814,7 @@ get_outer_encrypted_layer_plaintext(const hs_descriptor_t *desc, tor_assert(!fast_mem_is_zero((char *) ephemeral_pubkey->public_key, CURVE25519_PUBKEY_LEN));

- curve25519_public_to_base64(ephemeral_key_base64, ephemeral_pubkey); + curve25519_public_to_base64(ephemeral_key_base64, ephemeral_pubkey, true); smartlist_add_asprintf(lines, "%s %s\n", str_desc_auth_key, ephemeral_key_base64);

diff --git a/src/lib/crypt_ops/crypto_curve25519.h b/src/lib/crypt_ops/crypto_curve25519.h index 154a0b94bc..f1e5d1265d 100644 --- a/src/lib/crypt_ops/crypto_curve25519.h +++ b/src/lib/crypt_ops/crypto_curve25519.h @@ -9,6 +9,7 @@ #ifndef TOR_CRYPTO_CURVE25519_H #define TOR_CRYPTO_CURVE25519_H

+#include <stdbool.h> #include "lib/testsupport/testsupport.h" #include "lib/cc/torint.h" #include "lib/crypt_ops/crypto_digest.h" @@ -77,7 +78,8 @@ STATIC int curve25519_basepoint_impl(uint8_t *output, const uint8_t *secret); int curve25519_public_from_base64(curve25519_public_key_t *pkey, const char *input); void curve25519_public_to_base64(char *output, - const curve25519_public_key_t *pkey); + const curve25519_public_key_t *pkey, + bool pad);

void curve25519_set_impl_params(int use_ed); void curve25519_init(void); diff --git a/src/lib/crypt_ops/crypto_format.c b/src/lib/crypt_ops/crypto_format.c index 92b8b9372e..4483b7d2f5 100644 --- a/src/lib/crypt_ops/crypto_format.c +++ b/src/lib/crypt_ops/crypto_format.c @@ -131,9 +131,10 @@ crypto_read_tagged_contents_from_file(const char *fname, return r; }

-/** Encode <b>pkey</b> as a base64-encoded string, including trailing "=" - * characters, in the buffer <b>output</b>, which must have at least - * CURVE25519_BASE64_PADDED_LEN+1 bytes available. +/** Encode <b>pkey</b> as a base64-encoded string in the buffer <b>output</b>. + * If <b>pad</b> is false do not include trailing "=" characters, otherwise + * include them. <b>output</b> must have at least + * CURVE25519_BASE64_PADDED_LEN+1 bytes available, even if <b>pad</b> is false. * Can not fail. * * Careful! CURVE25519_BASE64_PADDED_LEN is one byte longer than @@ -141,17 +142,25 @@ crypto_read_tagged_contents_from_file(const char *fname, */ void curve25519_public_to_base64(char *output, - const curve25519_public_key_t *pkey) + const curve25519_public_key_t *pkey, bool pad) { - char buf[128]; - int n = base64_encode(buf, sizeof(buf), - (const char*)pkey->public_key, - CURVE25519_PUBKEY_LEN, 0); + int n, expected_len; + if (pad) { + n = base64_encode(output, CURVE25519_BASE64_PADDED_LEN+1, + (const char*)pkey->public_key, + CURVE25519_PUBKEY_LEN, 0); + expected_len = CURVE25519_BASE64_PADDED_LEN; + } else { + n = base64_encode_nopad(output, CURVE25519_BASE64_PADDED_LEN+1, + (const uint8_t*)pkey->public_key, + CURVE25519_PUBKEY_LEN); + expected_len = CURVE25519_BASE64_LEN; + } + /* These asserts should always succeed, unless there is a bug in * base64_encode(). */ - tor_assert(n == CURVE25519_BASE64_PADDED_LEN); - tor_assert(buf[CURVE25519_BASE64_PADDED_LEN] == '\0'); - memcpy(output, buf, CURVE25519_BASE64_PADDED_LEN+1); + tor_assert(n == expected_len); + tor_assert(output[expected_len] == '\0'); }

/** Try to decode a base64-encoded curve25519 public key from <b>input</b> @@ -162,11 +171,11 @@ curve25519_public_from_base64(curve25519_public_key_t *pkey, const char *input) { size_t len = strlen(input); - if (len == CURVE25519_BASE64_PADDED_LEN - 1) { + if (len == CURVE25519_BASE64_LEN) { /* not padded */ return digest256_from_base64((char*)pkey->public_key, input); } else if (len == CURVE25519_BASE64_PADDED_LEN) { - char buf[128]; + char buf[CURVE25519_BASE64_PADDED_LEN+1]; if (base64_decode(buf, sizeof(buf), input, len) != CURVE25519_PUBKEY_LEN) return -1; memcpy(pkey->public_key, buf, CURVE25519_PUBKEY_LEN); diff --git a/src/lib/defs/x25519_sizes.h b/src/lib/defs/x25519_sizes.h index acb08c5e6a..e650f5a350 100644 --- a/src/lib/defs/x25519_sizes.h +++ b/src/lib/defs/x25519_sizes.h @@ -36,6 +36,9 @@ /** Length of a Curve25519 key when encoded in base 64, with padding. */ #define CURVE25519_BASE64_PADDED_LEN 44

+/** Length of a Curve25519 key when encoded in base 64, without padding. */ +#define CURVE25519_BASE64_LEN 43 + /** Length of a Ed25519 key when encoded in base 64, without padding. */ #define ED25519_BASE64_LEN 43 /** Length of a Ed25519 signature when encoded in base 64, without padding. */ diff --git a/src/test/test_crypto.c b/src/test/test_crypto.c index 0d75a212e9..ffd6a25bd5 100644 --- a/src/test/test_crypto.c +++ b/src/test/test_crypto.c @@ -2107,21 +2107,21 @@ test_crypto_curve25519_encode(void *arg) { curve25519_secret_key_t seckey; curve25519_public_key_t key1, key2, key3; - char buf[64]; + char buf[64], buf_nopad[64];

(void)arg;

curve25519_secret_key_generate(&seckey, 0); curve25519_public_key_generate(&key1, &seckey); - curve25519_public_to_base64(buf, &key1); + curve25519_public_to_base64(buf, &key1, true); tt_int_op(CURVE25519_BASE64_PADDED_LEN, OP_EQ, strlen(buf));

tt_int_op(0, OP_EQ, curve25519_public_from_base64(&key2, buf)); tt_mem_op(key1.public_key,OP_EQ, key2.public_key, CURVE25519_PUBKEY_LEN);

- buf[CURVE25519_BASE64_PADDED_LEN - 1] = '\0'; - tt_int_op(CURVE25519_BASE64_PADDED_LEN-1, OP_EQ, strlen(buf)); - tt_int_op(0, OP_EQ, curve25519_public_from_base64(&key3, buf)); + curve25519_public_to_base64(buf_nopad, &key1, false); + tt_int_op(CURVE25519_BASE64_LEN, OP_EQ, strlen(buf_nopad)); + tt_int_op(0, OP_EQ, curve25519_public_from_base64(&key3, buf_nopad)); tt_mem_op(key1.public_key,OP_EQ, key3.public_key, CURVE25519_PUBKEY_LEN);

/* Now try bogus parses. */