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crypto: check DiffieHellman p and g params
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It's possible to pass in the prime and generator params as buffers
but that mode of input wasn't as rigorously checked as numeric input.

PR-URL: #32739
Fixes: #32738
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
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bnoordhuis authored and targos committed May 4, 2020
1 parent e07cca6 commit 83e165b
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Showing 2 changed files with 54 additions and 2 deletions.
25 changes: 23 additions & 2 deletions src/node_crypto.cc
Original file line number Diff line number Diff line change
Expand Up @@ -5136,6 +5136,14 @@ bool DiffieHellman::Init(int primeLength, int g) {

bool DiffieHellman::Init(const char* p, int p_len, int g) {
dh_.reset(DH_new());
if (p_len <= 0) {
BNerr(BN_F_BN_GENERATE_PRIME_EX, BN_R_BITS_TOO_SMALL);
return false;
}
if (g <= 1) {
DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_BAD_GENERATOR);
return false;
}
BIGNUM* bn_p =
BN_bin2bn(reinterpret_cast<const unsigned char*>(p), p_len, nullptr);
BIGNUM* bn_g = BN_new();
Expand All @@ -5151,10 +5159,23 @@ bool DiffieHellman::Init(const char* p, int p_len, int g) {

bool DiffieHellman::Init(const char* p, int p_len, const char* g, int g_len) {
dh_.reset(DH_new());
BIGNUM* bn_p =
BN_bin2bn(reinterpret_cast<const unsigned char*>(p), p_len, nullptr);
if (p_len <= 0) {
BNerr(BN_F_BN_GENERATE_PRIME_EX, BN_R_BITS_TOO_SMALL);
return false;
}
if (g_len <= 0) {
DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_BAD_GENERATOR);
return false;
}
BIGNUM* bn_g =
BN_bin2bn(reinterpret_cast<const unsigned char*>(g), g_len, nullptr);
if (BN_is_zero(bn_g) || BN_is_one(bn_g)) {
BN_free(bn_g);
DHerr(DH_F_DH_BUILTIN_GENPARAMS, DH_R_BAD_GENERATOR);
return false;
}
BIGNUM* bn_p =
BN_bin2bn(reinterpret_cast<const unsigned char*>(p), p_len, nullptr);
if (!DH_set0_pqg(dh_.get(), bn_p, nullptr, bn_g)) {
BN_free(bn_p);
BN_free(bn_g);
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31 changes: 31 additions & 0 deletions test/parallel/test-crypto-dh.js
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,37 @@ for (const bits of [-1, 0, 1]) {
});
}

// Through a fluke of history, g=0 defaults to DH_GENERATOR (2).
{
const g = 0;
crypto.createDiffieHellman('abcdef', g);
crypto.createDiffieHellman('abcdef', 'hex', g);
}

for (const g of [-1, 1]) {
const ex = {
code: 'ERR_OSSL_DH_BAD_GENERATOR',
name: 'Error',
message: /bad generator/,
};
assert.throws(() => crypto.createDiffieHellman('abcdef', g), ex);
assert.throws(() => crypto.createDiffieHellman('abcdef', 'hex', g), ex);
}

crypto.createDiffieHellman('abcdef', Buffer.from([2])); // OK

for (const g of [Buffer.from([]),
Buffer.from([0]),
Buffer.from([1])]) {
const ex = {
code: 'ERR_OSSL_DH_BAD_GENERATOR',
name: 'Error',
message: /bad generator/,
};
assert.throws(() => crypto.createDiffieHellman('abcdef', g), ex);
assert.throws(() => crypto.createDiffieHellman('abcdef', 'hex', g), ex);
}

{
const DiffieHellman = crypto.DiffieHellman;
const dh = DiffieHellman(p1, 'buffer');
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