From 1e8b392f53dbb9f9a20b1fe8bd3b7876be7ccb3b Mon Sep 17 00:00:00 2001 From: Tony Arcieri Date: Mon, 8 Aug 2022 08:23:43 -0600 Subject: [PATCH 1/2] Add `RsaPublicKey::new_with_max_size`; 4096-bit default max This constructor accepts a configurable maximum key size which can be used in applications that need to deal with unusually large RSA public keys, such as OpenPGP. With the ability to configure an upper limit, this makes it possible to lower the default maximum key size to 4096-bits, which is a reasonable upper limit for most applications. Fixes #166 --- src/key.rs | 47 ++++++++++++++++++++++++++++++++--------------- 1 file changed, 32 insertions(+), 15 deletions(-) diff --git a/src/key.rs b/src/key.rs index fe3a344..373ee1f 100644 --- a/src/key.rs +++ b/src/key.rs @@ -16,10 +16,6 @@ use crate::padding::PaddingScheme; use crate::raw::{DecryptionPrimitive, EncryptionPrimitive}; use crate::{oaep, pkcs1v15, pss}; -const MIN_PUB_EXPONENT: u64 = 2; -const MAX_PUB_EXPONENT: u64 = (1 << 33) - 1; -const MAX_MODULUS_BITS: usize = 16384; - pub trait PublicKeyParts { /// Returns the modulus of the key. fn n(&self) -> &BigUint; @@ -229,11 +225,27 @@ impl PublicKey for RsaPublicKey { } impl RsaPublicKey { - /// Create a new key from its components. + /// Minimum value of the public exponent `e`. + pub const MIN_PUB_EXPONENT: u64 = 2; + + /// Maximum value of the public exponent `e`. + pub const MAX_PUB_EXPONENT: u64 = (1 << 33) - 1; + + /// Maximum size of the modulus `n` in bits. + pub const MAX_SIZE: usize = 4096; + + /// Create a new public key from its components. + /// + /// This function accepts public keys with a modulus size up to 4096-bits, + /// i.e. [`RsaPublicKey::MAX_SIZE`]. pub fn new(n: BigUint, e: BigUint) -> Result { - let k = RsaPublicKey { n, e }; - check_public(&k)?; + Self::new_with_max_size(n, e, Self::MAX_SIZE) + } + /// Create a new public key from its components. + pub fn new_with_max_size(n: BigUint, e: BigUint, max_size: usize) -> Result { + let k = RsaPublicKey { n, e }; + check_public_with_max_size(&k, max_size)?; Ok(k) } } @@ -336,10 +348,9 @@ impl RsaPrivateKey { /// Get the public key from the private key, cloning `n` and `e`. /// /// Generally this is not needed since `RsaPrivateKey` implements the `PublicKey` trait, - /// but it can occationally be useful to discard the private information entirely. + /// but it can occasionally be useful to discard the private information entirely. pub fn to_public_key(&self) -> RsaPublicKey { - // Safe to unwrap since n and e are already verified. - RsaPublicKey::new(self.n().clone(), self.e().clone()).unwrap() + self.pubkey_components.clone() } /// Performs some calculations to speed up private key operations. @@ -409,9 +420,9 @@ impl RsaPrivateKey { } /// Performs basic sanity checks on the key. - /// Returns `Ok(())` if everything is good, otherwise an approriate error. + /// Returns `Ok(())` if everything is good, otherwise an appropriate error. pub fn validate(&self) -> Result<()> { - check_public(self)?; + check_public_with_max_size(self, RsaPublicKey::MAX_SIZE)?; // Check that Πprimes == n. let mut m = BigUint::one(); @@ -549,7 +560,13 @@ impl RsaPrivateKey { /// Check that the public key is well formed and has an exponent within acceptable bounds. #[inline] pub fn check_public(public_key: &impl PublicKeyParts) -> Result<()> { - if public_key.n().bits() > MAX_MODULUS_BITS { + check_public_with_max_size(public_key, RsaPublicKey::MAX_SIZE) +} + +/// Check that the public key is well formed and has an exponent within acceptable bounds. +#[inline] +fn check_public_with_max_size(public_key: &impl PublicKeyParts, max_size: usize) -> Result<()> { + if public_key.n().bits() > max_size { return Err(Error::ModulusTooLarge); } @@ -558,11 +575,11 @@ pub fn check_public(public_key: &impl PublicKeyParts) -> Result<()> { .to_u64() .ok_or(Error::PublicExponentTooLarge)?; - if e < MIN_PUB_EXPONENT { + if e < RsaPublicKey::MIN_PUB_EXPONENT { return Err(Error::PublicExponentTooSmall); } - if e > MAX_PUB_EXPONENT { + if e > RsaPublicKey::MAX_PUB_EXPONENT { return Err(Error::PublicExponentTooLarge); } From 2ff7521e9448685c3b0425b18db279c3189825b5 Mon Sep 17 00:00:00 2001 From: Tony Arcieri Date: Mon, 8 Aug 2022 16:16:44 -0600 Subject: [PATCH 2/2] add test --- src/errors.rs | 2 +- src/key.rs | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 75 insertions(+), 2 deletions(-) diff --git a/src/errors.rs b/src/errors.rs index ead6be1..666ada0 100644 --- a/src/errors.rs +++ b/src/errors.rs @@ -1,7 +1,7 @@ pub type Result = core::result::Result; /// Error types -#[derive(Debug)] +#[derive(Debug, Eq, PartialEq)] #[non_exhaustive] pub enum Error { InvalidPaddingScheme, diff --git a/src/key.rs b/src/key.rs index 373ee1f..987f0a6 100644 --- a/src/key.rs +++ b/src/key.rs @@ -422,7 +422,7 @@ impl RsaPrivateKey { /// Performs basic sanity checks on the key. /// Returns `Ok(())` if everything is good, otherwise an appropriate error. pub fn validate(&self) -> Result<()> { - check_public_with_max_size(self, RsaPublicKey::MAX_SIZE)?; + check_public(self)?; // Check that Πprimes == n. let mut m = BigUint::one(); @@ -618,6 +618,7 @@ mod tests { use alloc::string::String; use digest::{Digest, DynDigest}; + use hex_literal::hex; use num_traits::{FromPrimitive, ToPrimitive}; use rand_chacha::{ rand_core::{RngCore, SeedableRng}, @@ -818,6 +819,78 @@ mod tests { .unwrap(); } + #[test] + fn reject_oversized_private_key() { + // -----BEGIN PUBLIC KEY----- + // MIIEIjANBgkqhkiG9w0BAQEFAAOCBA8AMIIECgKCBAEAkMBiB8qsNVXAsJR6Xoto + // H1r2rtZl/xzUK2tIfy99aPE489u+5tLxCQhQf+a89158vSDpr2/xwgK8w9u0Xpu2 + // m7XRKjVMS0Y6UIINFoeTc87rVXT92Scr47kNVcGmSFXez4BSDpS+LKpWwXN+0AQu + // +cmcfdtsx2862iEbqQvq4PwKGQJOdOR0yldH8O4yeJK/buvIOXRHjb++vtQND/xi + // bFGAcd9WJqvaOG7tclhbZ277mbO6ER+y9Lj7AyO8ywybWqNeHaVPHMysPhT7HUWI + // 17m59i1OpuVwwEnvzDQQEUf9d5hUmkLYb5qQzuf6Ddnx/04QJCKAgkhyr9CXgnV6 + // vEZ3PKtpicCHRxk7eqTEmgBlgwqH5vflRFV1iywQMXJnuRhzWOQaXl/vb8v4HIvF + // 4TatEZKqfzpbyScLIiYbPEAhHXKdZMd2zY8hkSbicifePApAZmuNpAxxJDZzphh7 + // r4lD6t8MPT/RUAdtrZfihqaBhduFI6YeVIy6emg05M6YWvlUyer7nYGaPRS1JqD4 + // 0v7xOtme5I8Qw6APiFPXhTqBK3occr7TgGb3V3lpC8Eq+esNHrji98R1fITkFXJW + // KdFcTWjBghPxiobUzMCFUrPIDJcWXeBzrARAryU+hXjEiFfzluXrps0B7RJQ/rLD + // LXeTn4vovUeHQVHa7YfoyWMy9pfqeVC+56LBK7SEIAvL0I3lrq5vIv+ZIuOAdbVg + // JiRy8DneCOk2LP3RnA8M0HSevYW93DiC+4h/l4ntjjiOfi6yRVOZ8WbVyXZ/83j4 + // 6+pGWgvi0uMyb+btgOXjBQv7bGqdyHMc5Lqk5bF7ExETx51vKQMYCV4351caS6aX + // q16lYZATHgbTADEAZHdroDMJB+HMQaze9O6qU5ZO8wxxAjw89xry0dnoOQD/yA4H + // 7CRCo9vVDpV2hqIvHY9RI2T7cek28kmQpKvNvvK+ovmM138dHKViWULHk0fBRt7m + // 4wQ+tiL2PmJ/Tr8g1gVhM6S9D1XdE9z0KeDnODCWn1Q8sx2G2ah4ynnYQURDWcwO + // McAoP6bdJ7cCt+4F2tEsMPf4S/EwlnjvuNoQjvztxCPahYe9EnyggtQXyHJveIn7 + // gDJsP6b93VB6x4QbLy5ch4DUhqDWginuKVeo7CTgDkq03j/IEaS1BHwreSDQceny + // +bYWONwV+4TMpGytKOHvU5288kmHbyZHdXuaXk8LLqbnqr30fa6Cbp4llCi9sH5a + // Kmi5jxQfVTe+elkMs7oVsLsVgkZS6NqPcOuEckAFijNqG223+IJoqvifCzO5Bdcs + // JTOLE+YaUYc8LUJwIaPykgcXmtMvQjeT8MCQ3aAlzkHfDpSvvICrXtqbGiaKolU6 + // mQIDAQAB + // -----END PUBLIC KEY----- + + let n = BigUint::from_bytes_be(&hex!( + " + 90c06207caac3555c0b0947a5e8b681f5af6aed665ff1cd42b6b487f2f7d68f1 + 38f3dbbee6d2f10908507fe6bcf75e7cbd20e9af6ff1c202bcc3dbb45e9bb69b + b5d12a354c4b463a50820d16879373ceeb5574fdd9272be3b90d55c1a64855de + cf80520e94be2caa56c1737ed0042ef9c99c7ddb6cc76f3ada211ba90beae0fc + 0a19024e74e474ca5747f0ee327892bf6eebc83974478dbfbebed40d0ffc626c + 518071df5626abda386eed72585b676efb99b3ba111fb2f4b8fb0323bccb0c9b + 5aa35e1da54f1cccac3e14fb1d4588d7b9b9f62d4ea6e570c049efcc34101147 + fd7798549a42d86f9a90cee7fa0dd9f1ff4e10242280824872afd09782757abc + 46773cab6989c08747193b7aa4c49a0065830a87e6f7e54455758b2c10317267 + b9187358e41a5e5fef6fcbf81c8bc5e136ad1192aa7f3a5bc9270b22261b3c40 + 211d729d64c776cd8f219126e27227de3c0a40666b8da40c71243673a6187baf + 8943eadf0c3d3fd150076dad97e286a68185db8523a61e548cba7a6834e4ce98 + 5af954c9eafb9d819a3d14b526a0f8d2fef13ad99ee48f10c3a00f8853d7853a + 812b7a1c72bed38066f75779690bc12af9eb0d1eb8e2f7c4757c84e415725629 + d15c4d68c18213f18a86d4ccc08552b3c80c97165de073ac0440af253e8578c4 + 8857f396e5eba6cd01ed1250feb2c32d77939f8be8bd47874151daed87e8c963 + 32f697ea7950bee7a2c12bb484200bcbd08de5aeae6f22ff9922e38075b56026 + 2472f039de08e9362cfdd19c0f0cd0749ebd85bddc3882fb887f9789ed8e388e + 7e2eb2455399f166d5c9767ff378f8ebea465a0be2d2e3326fe6ed80e5e3050b + fb6c6a9dc8731ce4baa4e5b17b131113c79d6f290318095e37e7571a4ba697ab + 5ea56190131e06d300310064776ba0330907e1cc41acdef4eeaa53964ef30c71 + 023c3cf71af2d1d9e83900ffc80e07ec2442a3dbd50e957686a22f1d8f512364 + fb71e936f24990a4abcdbef2bea2f98cd77f1d1ca5625942c79347c146dee6e3 + 043eb622f63e627f4ebf20d6056133a4bd0f55dd13dcf429e0e73830969f543c + b31d86d9a878ca79d841444359cc0e31c0283fa6dd27b702b7ee05dad12c30f7 + f84bf1309678efb8da108efcedc423da8587bd127ca082d417c8726f7889fb80 + 326c3fa6fddd507ac7841b2f2e5c8780d486a0d68229ee2957a8ec24e00e4ab4 + de3fc811a4b5047c2b7920d071e9f2f9b61638dc15fb84cca46cad28e1ef539d + bcf249876f2647757b9a5e4f0b2ea6e7aabdf47dae826e9e259428bdb07e5a2a + 68b98f141f5537be7a590cb3ba15b0bb15824652e8da8f70eb847240058a336a + 1b6db7f88268aaf89f0b33b905d72c25338b13e61a51873c2d427021a3f29207 + 179ad32f423793f0c090dda025ce41df0e94afbc80ab5eda9b1a268aa2553a99" + )); + + let e = BigUint::from_u64(65537).unwrap(); + + assert_eq!( + RsaPublicKey::new(n, e).err().unwrap(), + Error::ModulusTooLarge + ); + } + fn get_private_key() -> RsaPrivateKey { // -----BEGIN RSA PRIVATE KEY----- // MIIEpAIBAAKCAQEA05e4TZikwmE47RtpWoEG6tkdVTvwYEG2LT/cUKBB4iK49FKW