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More robustly validate signature inputs, closes #313

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This commit is contained in:
Nik Bougalis
2014-03-26 12:11:28 +07:00
parent f124a34730
commit c51644f1b9
1 changed files with 58 additions and 15 deletions
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73
src/ripple/sslutil/impl/ECDSACanonical.cpp
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@@ -88,18 +88,21 @@ namespace detail {
BigNum m_bn;
public:
SignaturePart (unsigned char const* sig, size_t len)
SignaturePart (unsigned char const* sig, size_t size)
: m_skip (0)
{
// The format is: <02> <len> <sig>
if ((sig[0] != 0x02) || (len < 3))
// The format is: <02> <length of signature> <signature>
if ((sig[0] != 0x02) || (size < 3))
return;
size_t sigLen = sig[1];
size_t const len (sig[1]);
// Can't be longer than the data we have and must
// be between 1 and 33 bytes.
if ((sigLen > len) || (sigLen < 2) || (sigLen > 33))
// Claimed length can't be longer than amount of data available
if (len > (size - 2))
return;
// Signature must be between 1 and 33 bytes.
if ((len < 1) || (len > 33))
return;
// The signature can't be negative
@@ -114,9 +117,10 @@ namespace detail {
if ((sig[2] == 0) && ((sig[3] & 0x80) == 0))
return;
// Load the signature but skip the marker prefix and length
if (m_bn.set (sig + 2, sigLen))
m_skip = sigLen + 2;
// Load the signature (ignore the marker prefix and length) and if
// successful, count the number of bytes we consumed.
if (m_bn.set (sig + 2, len))
m_skip = len + 2;
}
bool valid () const
@@ -161,7 +165,7 @@ bool isCanonicalECDSASig (void const* vSig, size_t sigLen, ECDSA strict_param)
unsigned char const* sig = reinterpret_cast<unsigned char const*> (vSig);
if ((sigLen < 10) || (sigLen > 72))
if ((sigLen < 8) || (sigLen > 72))
return false;
if ((sig[0] != 0x30) || (sig[1] != (sigLen - 2)))
@@ -311,8 +315,7 @@ public:
return b;
}
/** Verifies that a signature is valid.
Valid signatures may not be canonical
/** Verifies that a signature is syntactically valid.
*/
bool isValid (std::string const& hex)
{
@@ -320,8 +323,7 @@ public:
return isCanonicalECDSASig (&j[0], j.size(), ECDSA::not_strict);
}
/** Verifies that a signature is canonical.
Canonical signatures are valid.
/** Verifies that a signature is syntactically valid and in canonical form.
*/
bool isStrictlyCanonical (std::string const& hex)
{
@@ -386,6 +388,12 @@ public:
{
testcase ("Canonical signature checks", abort_on_fail);
// r and s 1 byte 1
expect (isValid ("3006"
"020101"
"020102"),
"Well-formed short signature");
expect (isValid ("3044"
"02203932c892e2e550f3af8ee4ce9c215a87f9bb831dcac87b2838e2c2eaa891df0c"
"022030b61dd36543125d56b9f9f3a1f53189e5af33cdda8d77a5209aec03978fa001"),
@@ -437,6 +445,41 @@ public:
"0200"),
"tooshort");
expect (!isValid ("3006"
"020101"
"020202"),
"Slen-Overlong");
expect (!isValid ("3006"
"020701"
"020102"),
"Rlen-Overlong-OOB");
expect (!isValid ("3006"
"020401"
"020102"),
"Rlen-Overlong-OOB");
expect (!isValid ("3006"
"020501"
"020102"),
"Rlen-Overlong-OOB");
expect (!isValid ("3006"
"020201"
"020102"),
"Rlen-Overlong");
expect (!isValid ("3006"
"020301"
"020202"),
"Rlen Overlong and Slen-Overlong");
expect (!isValid ("3006"
"020401"
"020202"),
"Rlen Overlong and OOB and Slen-Overlong");
expect (!isValid("3047"
"0221005990e0584b2b238e1dfaad8d6ed69ecc1a4a13ac85fc0b31d0df395eb1ba6105"
"022200002d5876262c288beb511d061691bf26777344b702b00f8fe28621fe4e566695ed"),