I have a public key and an encrypted string. I could encrypt with the publickey successfully.But when i try to decrypt using the publickey it fails. I mean when i pass the publickey toseckeyDecrypt it fails.
I have Googled and found out that, by default kSecAttrCanDecrypt is false for public keys.So When i import the public key, i have added this particular line ,
[publicKeyAttr setObject:(id)kCFBooleanTrue forKey:(id)kSecAttrCanDecrypt];
But there is no improvement it still fails. Please somebody help.
EDIT:
Apple's Certificate,Key and Trust Services Says,
kSecAttrCanEncrypt Default false for private keys, true for public keys.
kSecAttrCanDecrypt Default true for private keys, false for public keys.
Which means, the values can be changed right?. My server does not sign(Convert as a digest) the content. They just encrypt using the private key which is to be decrypted at my(in iphone) end. Is that possible?.
The point of asymmetric cryptography is that you encrypt with the public key and decrypt with the private key.
EDIT: If you're signing and verifying, you should use the associated APIs. For example, you can check this capability with kSecAttrCanSign and kSecAttrCanVerify.
Related
I'm trying to implement MTLS client authentication using AWS ACM Private CA to issue X.509 client certificates.
The certificate and the correlating private key is supposed to be stored in a password protected PKCS#12 file.
The private key will also be used by the client to sign data.
If I request a new certificate using aws-acm-sdk:
RequestCertificateResult response = acm.requestCertificate(new RequestCertificateRequest()
.withCertificateAuthorityArn(CA_ARN)
.withIdempotencyToken("1234")
.withDomainName("localhost.com"));
return response.getCertificateArn();
And then export the it using the arn, I get a certificate, certificateChain and a privateKey as strings.
ExportCertificateResult response = acm.exportCertificate(new ExportCertificateRequest()
.withCertificateArn(certificateArn)
.withPassphrase(ByteBuffer.wrap(password.getBytes())));
String certificate = response.getCertificate();
String certificateChain = response.getCertificateChain();
String privateKey = response.getPrivateKey();
But I'm not able to add any type of identifier that let's me tie the certificate to a user during authentication (I'm using Java and Spring security x509 authentication, which extracts e.g. the subject CN (Common Name) from the certificate which then can be used to identify a user).
If I want to add custom attributes to the certificate, I need to issue a certificate through the aws-acm-pca-sdk:
IssueCertificateRequest request = new IssueCertificateRequest()
.withCertificateAuthorityArn(CA_ARN)
.withCsr(stringToByteBuffer(getCSR()))
.withTemplateArn("arn:aws:acm-pca:::template/EndEntityClientAuthCertificate_APIPassthrough/V1")
.withSigningAlgorithm(SigningAlgorithm.SHA256WITHRSA)
.withValidity(new Validity()
.withValue(365L)
.withType(ValidityPeriodType.DAYS))
.withIdempotencyToken(userId)
.withApiPassthrough(new ApiPassthrough()
.withSubject(new ASN1Subject()
.withCustomAttributes(List.of(
new CustomAttribute()
.withObjectIdentifier("1.3.6.1.4.1") // CustomOID
.withValue("userId")))));
return acmPca.issueCertificate(request).getCertificateArn();
But if I use the sdk to get the certificate, it doesn't contain any private key.
GetCertificateResult response = acmPca.getCertificate(new GetCertificateRequest()
.withCertificateAuthorityArn(CA_ARN)
.withCertificateArn(certificateArn));
String certificate = response.getCertificate();
String certificateChain = response.getCertificateChain();
So, when I read documentation I found that I need to import it to ACM in order to export it and get the private key.
But in order to import it to ACM I also need to provide the private key..
But as I understand it, the private key should be used when issuing the certificate in the first place?
Should I create a new public/private key pair using KMS or what am I supposed to do?
Im confused.. Please help!
I had misinterpreted the responsibility of the PCA.
The PCA is only responsible for issuing certificates, not keys or even CSR (Certificate Signing Requests).
I assumed that the CSR were created by PCA, so the getCSR() method actually fetched the CA's CSR from PCA, while the actual CSR should be generated internally using a private key which has been generated either programmatically or using KMS.
I use python pycryptodome rto generate my private and public key. This is one example of a public key that I am generating:
(n=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, e=0x10001)
I generate it using this piece of code:
keyPair = RSA.generate(bits=2048)
publicKey = f"(n={hex(keyPair.n)}, e={hex(keyPair.e)})"
Somehow, this doesn't look correct to me, because usually, when I create a key using mac os or other method, I have something like
---BEGIN PRIVATE KEY aksdjbvioasv.....(key itself here....) ---END PUBLIC KEY
What am I msising so that my RSA key is generated correctly?
I solved it by doing
pubKey = keyPair.publickey()
pubKeyPEM = pubKey.exportKey()
print("pubKey PEM is:")
print(pubKeyPEM)
Now I get the proper format, that I can now write into a file!
I am currently working on encryption in my flutter app wherein I am using RSA key-pair generator to get public and private key using the following code-
import 'package:rsa_encrypt/rsa_encrypt.dart';
import 'package:pointycastle/api.dart' as crypto;
//Future to hold our KeyPair
Future<crypto.AsymmetricKeyPair> futureKeyPair;
//to store the KeyPair once we get data from our future
crypto.AsymmetricKeyPair keyPair;
Future<crypto.AsymmetricKeyPair<crypto.PublicKey, crypto.PrivateKey>> getKeyPair()
{
var helper = RsaKeyHelper();
return helper.computeRSAKeyPair(helper.getSecureRandom());
}
Now I want to get the keyPair.publicKey in string format but if i print keyPair.publicKey, it shows "Instance of RSA publicKey" . How can I get it in string format??
It is always best to use standardized formats when saving public keys. For RSA public keys you can store them in layers, much like a Matroesjka doll.
Encode the public key in the ASN.1 / DER format specified in the PKCS#1 RSA standard;
Encode that public key in a format called SubjectPublicKeyInfo which is part of the X.509 specifications - it indicates that this is indeed an RSA key;
Apply so called PEM "ASCII armor", which consists of a header & footer line indicating the generic SubjectPublicKeyFormat (just PUBLIC KEY), with a multi-line base 64 encoding of the public key from step 2 in between.
Sounds like a lot of work, but if you look here you'll find handy methods called encodePublicKeyToPem and parsePublicKeyFromPem that do these 3 steps for you (it actually does both 1 and 2 in the same function, which is a bit of a shame but not that important).
These keys are rather portable and are also usable by e.g. OpenSSL or PGP.
Using windows CryptoAPI, is it possible to get public RSA key from a private key which was imported (not generated)?
If I use CryptGenKey, I can call CryptExportPublicKeyInfo and CryptImportPublicKeyInfo to obtain the public key handle. However, when I try to do the same thing with private key decoded from PEM and imported using:
CryptImportKey(hCSP, pKeyBuf, cbKeyBuf, 0, CRYPT_EXPORTABLE, &hPrivKey)
import of the private key succeeds and I have a valid handle but the subsequent call to CryptExportPublicKeyInfo fails with "Key does not exist" error. It looks like there's another call missing between CryptImportKey and CryptExportPublicKeyInfo, but I can not find that API call.
The problem with exporting/importing the public key was because private key was generated using AT_SIGNATURE, instead of AT_EXCHANGE. See the explanation and the example code
Currently we have a routine that Signs a byte[] given a certificate (and it's private key). However, the type of certificate/keys is hardcoded as "Certificate with RSA keys". That code is :
public byte[] Sign(byte[] bytesToSign, bool fOAEP, X509Certificate2 certificate)
{
using (RSACryptoServiceProvider provider = new RSACryptoServiceProvider())
{
// HACK: Round-trip the key to XML and back, to get provider type working
// as 'Microsoft Enhanced RSA and AES Cryptographic Provider' (for
// SHA256/SHA512 signing hash) instead of 'Microsoft Enhanced
// Cryptographic Provider v1.0' (that limits us to SHA1)
string publicKeyXml = certificate.PrivateKey.ToXmlString(true);
provider.FromXmlString(publicKeyXml);
// We use the private key to sign.
return provider.SignData(bytesToSign, CryptoConfig.MapNameToOID("SHA512"));
}
}
We would like to make it more flexible where if the certificate uses RSA keys, we process it one way but if it uses EC keys, then we process it differently. Basically the Crypto Service Provider type would be of a different type.
So the core question is:
Given a certificate with public+private keys (for signing) OR a certificate with just public keys (for verifying), how do you determine the types of keys used by the certificate?
I'm open to standard .NET libs or even BouncyCastle.Org libs.
You can check key type (algorithm) via certificate.PublicKey.Oid.
Here you can see supported by Microsoft OIDs: http://msdn.microsoft.com/en-us/library/ff635835.aspx
Other OIDs can be checked at oid-info.com