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LibCrypto: Do not trim leading zeros in export_data by default

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This fixes the issue with the exported data having a leading zero,
causing RSA::encrypt to trim the block down, and ruining the encryption.

Fixes #2691 :^)
This commit is contained in:
AnotherTest 2020-07-31 13:33:14 +04:30 • committed by Andreas Kling
parent 180207062c
commit b00ffc860b
6 changed files with 27 additions and 19 deletions
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20
Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
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@ -55,21 +55,23 @@ UnsignedBigInteger UnsignedBigInteger::create_invalid()
return invalid;
}
size_t UnsignedBigInteger::export_data(Bytes data) const
size_t UnsignedBigInteger::export_data(Bytes data, bool remove_leading_zeros) const
{
size_t word_count = trimmed_length();
size_t out = 0;
if (word_count > 0) {
ssize_t leading_zeros = -1;
u32 word = m_words[word_count - 1];
for (size_t i = 0; i < sizeof(u32); i++) {
u8 byte = (u8)(word >> ((sizeof(u32) - i - 1) * 8));
data[out++] = byte;
if (leading_zeros < 0 && byte != 0)
leading_zeros = (int)i;
if (remove_leading_zeros) {
u32 word = m_words[word_count - 1];
for (size_t i = 0; i < sizeof(u32); i++) {
u8 byte = (u8)(word >> ((sizeof(u32) - i - 1) * 8));
data[out++] = byte;
if (leading_zeros < 0 && byte != 0)
leading_zeros = (int)i;
}
}
for (size_t i = word_count - 1; i > 0; i--) {
word = m_words[i - 1];
for (size_t i = word_count - (remove_leading_zeros ? 1 : 0); i > 0; i--) {
auto word = m_words[i - 1];
data[out++] = (u8)(word >> 24);
data[out++] = (u8)(word >> 16);
data[out++] = (u8)(word >> 8);