Fix Android Keystore KeyPairGenerator for RSA PSS keys.
This fixes a bug where key pair generation fails for RSA signing keys
which are not authorized for PKCS#1 signature padding, such as keys
authorized only for the RSA PSS signature padding scheme.
The issue was that the KeyPairGenerator was failing when attempting to
sign the self-signed certificate (needed by Android Keystore) using
PKCS#1 padding for which such keys are not authorized. The solution is
to not attempt to sign these certificates and instead use a fake
signature.
Bug: 21809600
Change-Id: I4f04fcf78174937046d2534e0485c6940eae673f
diff --git a/keystore/java/android/security/keystore/AndroidKeyStoreKeyPairGeneratorSpi.java b/keystore/java/android/security/keystore/AndroidKeyStoreKeyPairGeneratorSpi.java
index 35af34f..a6db228 100644
--- a/keystore/java/android/security/keystore/AndroidKeyStoreKeyPairGeneratorSpi.java
+++ b/keystore/java/android/security/keystore/AndroidKeyStoreKeyPairGeneratorSpi.java
@@ -703,6 +703,36 @@
}
case KeymasterDefs.KM_ALGORITHM_RSA:
{
+ // Check whether this key is authorized for PKCS#1 signature padding.
+ // We use Bouncy Castle to generate self-signed RSA certificates. Bouncy Castle
+ // only supports RSA certificates signed using PKCS#1 padding scheme. The key needs
+ // to be authorized for PKCS#1 padding or padding NONE which means any padding.
+ boolean pkcs1SignaturePaddingSupported = false;
+ for (int keymasterPadding : KeyProperties.SignaturePadding.allToKeymaster(
+ spec.getSignaturePaddings())) {
+ if ((keymasterPadding == KeymasterDefs.KM_PAD_RSA_PKCS1_1_5_SIGN)
+ || (keymasterPadding == KeymasterDefs.KM_PAD_NONE)) {
+ pkcs1SignaturePaddingSupported = true;
+ break;
+ }
+ }
+ if (!pkcs1SignaturePaddingSupported) {
+ // Keymaster doesn't distinguish between encryption padding NONE and signature
+ // padding NONE. In the Android Keystore API only encryption padding NONE is
+ // exposed.
+ for (int keymasterPadding : KeyProperties.EncryptionPadding.allToKeymaster(
+ spec.getEncryptionPaddings())) {
+ if (keymasterPadding == KeymasterDefs.KM_PAD_NONE) {
+ pkcs1SignaturePaddingSupported = true;
+ break;
+ }
+ }
+ }
+ if (!pkcs1SignaturePaddingSupported) {
+ // Key not authorized for PKCS#1 signature padding -- can't sign
+ return null;
+ }
+
Set<Integer> availableKeymasterDigests = getAvailableKeymasterSignatureDigests(
spec.getDigests(),
AndroidKeyStoreBCWorkaroundProvider.getSupportedEcdsaSignatureDigests());