diff options
author | lloyd <[email protected]> | 2015-02-05 07:44:25 +0000 |
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committer | lloyd <[email protected]> | 2015-02-05 07:44:25 +0000 |
commit | cb0f83ae63c4555cbdd0607e3a5f6e9260c0d19c (patch) | |
tree | 4981027a25fa8074177b97c3a3ca7431f3337deb /src/lib/misc/srp6/srp6.cpp | |
parent | 2c14faf0aa1cfe0f8d70af1938dcad5b4d6d3b59 (diff) |
Clean up root dir, remove some unneeded dependencies
Diffstat (limited to 'src/lib/misc/srp6/srp6.cpp')
-rw-r--r-- | src/lib/misc/srp6/srp6.cpp | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/src/lib/misc/srp6/srp6.cpp b/src/lib/misc/srp6/srp6.cpp new file mode 100644 index 000000000..d3f7338bd --- /dev/null +++ b/src/lib/misc/srp6/srp6.cpp @@ -0,0 +1,157 @@ +/* +* SRP-6a (RFC 5054 compatatible) +* (C) 2011,2012 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#include <botan/srp6.h> +#include <botan/dl_group.h> +#include <botan/numthry.h> +#include <botan/lookup.h> + +namespace Botan { + +namespace { + +BigInt hash_seq(const std::string& hash_id, + size_t pad_to, + const BigInt& in1, + const BigInt& in2) + { + std::unique_ptr<HashFunction> hash_fn(get_hash(hash_id)); + + hash_fn->update(BigInt::encode_1363(in1, pad_to)); + hash_fn->update(BigInt::encode_1363(in2, pad_to)); + + return BigInt::decode(hash_fn->final()); + } + +BigInt compute_x(const std::string& hash_id, + const std::string& identifier, + const std::string& password, + const std::vector<byte>& salt) + { + std::unique_ptr<HashFunction> hash_fn(get_hash(hash_id)); + + hash_fn->update(identifier); + hash_fn->update(":"); + hash_fn->update(password); + + secure_vector<byte> inner_h = hash_fn->final(); + + hash_fn->update(salt); + hash_fn->update(inner_h); + + secure_vector<byte> outer_h = hash_fn->final(); + + return BigInt::decode(outer_h); + } + +} + +std::string srp6_group_identifier(const BigInt& N, const BigInt& g) + { + /* + This function assumes that only one 'standard' SRP parameter set has + been defined for a particular bitsize. As of this writing that is the case. + */ + try + { + const std::string group_name = "modp/srp/" + std::to_string(N.bits()); + + DL_Group group(group_name); + + if(group.get_p() == N && group.get_g() == g) + return group_name; + + throw std::runtime_error("Unknown SRP params"); + } + catch(...) + { + throw Invalid_Argument("Bad SRP group parameters"); + } + } + +std::pair<BigInt, SymmetricKey> +srp6_client_agree(const std::string& identifier, + const std::string& password, + const std::string& group_id, + const std::string& hash_id, + const std::vector<byte>& salt, + const BigInt& B, + RandomNumberGenerator& rng) + { + DL_Group group(group_id); + const BigInt& g = group.get_g(); + const BigInt& p = group.get_p(); + + const size_t p_bytes = group.get_p().bytes(); + + if(B <= 0 || B >= p) + throw std::runtime_error("Invalid SRP parameter from server"); + + BigInt k = hash_seq(hash_id, p_bytes, p, g); + + BigInt a(rng, 256); + + BigInt A = power_mod(g, a, p); + + BigInt u = hash_seq(hash_id, p_bytes, A, B); + + const BigInt x = compute_x(hash_id, identifier, password, salt); + + BigInt S = power_mod((B - (k * power_mod(g, x, p))) % p, (a + (u * x)), p); + + SymmetricKey Sk(BigInt::encode_1363(S, p_bytes)); + + return std::make_pair(A, Sk); + } + +BigInt generate_srp6_verifier(const std::string& identifier, + const std::string& password, + const std::vector<byte>& salt, + const std::string& group_id, + const std::string& hash_id) + { + const BigInt x = compute_x(hash_id, identifier, password, salt); + + DL_Group group(group_id); + return power_mod(group.get_g(), x, group.get_p()); + } + +BigInt SRP6_Server_Session::step1(const BigInt& v, + const std::string& group_id, + const std::string& hash_id, + RandomNumberGenerator& rng) + { + DL_Group group(group_id); + const BigInt& g = group.get_g(); + const BigInt& p = group.get_p(); + + m_p_bytes = p.bytes(); + m_v = v; + m_b = BigInt(rng, 256); + m_p = p; + m_hash_id = hash_id; + + const BigInt k = hash_seq(hash_id, m_p_bytes, p, g); + + m_B = (v*k + power_mod(g, m_b, p)) % p; + + return m_B; + } + +SymmetricKey SRP6_Server_Session::step2(const BigInt& A) + { + if(A <= 0 || A >= m_p) + throw std::runtime_error("Invalid SRP parameter from client"); + + const BigInt u = hash_seq(m_hash_id, m_p_bytes, A, m_B); + + const BigInt S = power_mod(A * power_mod(m_v, u, m_p), m_b, m_p); + + return BigInt::encode_1363(S, m_p_bytes); + } + +} |