Question I'm encountering a very strange RSA issue on iOS. I'm using a 1024-bit RSA key pair generated by SecKeyGeneratePair. Public Key MIGJAoGBAK2wYDpTcGxFDe+0SwUj4twWOQWfWE+pvbgoUFsXZ/XBplEv7qlruq8ZutG+q7qW2M1983V5HzWGmtDrz2l8vLHYNKaBqEGYAtlYIePBq6+lfsUj2qmFE5Uui8R44KLz8i8QqMxYJUQoeUY3JxHeOe4DnUMWK3+X2nWWv4YWv9qxAgMBAAE= Private Key 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 Test Data Plaintext: SO202605140735073974 Encrypted ciphertext (Base64): AAKhsQxaEVqqZbFLUzC1+8uzdyCDVxzkTbq37pea6cgLlCTOniYeZQVwaOIRdioQmZ/M/0q33l0votNRWZje8bj4Km0vQF2NjvX+8EjPg6T6OsJKEt/KZf+bX6+PoNooSh1tC9H/HVFhhgNJdpKj9s/Fdl3eLH4qEsmQ25FS53M= After calling SecKeyDecrypt, I get the following decrypted bytes: 4d48734341514177457759484b6f5a497a6a3043415159494b6f5a497a6a304441514545595442664167454242426835707a4b493973744f4e42416b4a4757646e5035465842546d386e555272565367436759494b6f5a497a6a3044415147684e414d794141545a542b4a49746b4a4e647554424e70624d336f324d7a654e5565306f6e4e617a623767645975303370712f2f4271505861397747504e4575462b7145786a4c633d However: NSString *result = [[NSString alloc] initWithData:plainData encoding:NSUTF8StringEncoding]; returns nil. Additional Information This RSA key pair works correctly for many other plaintext values. The failure only occurs when encrypting and decrypting this specific string: SO202605140735073974 The RSA key pair is generated using: SecKeyGeneratePair(...) with a 1024-bit key size. Encryption and decryption use the Security framework APIs: SecKeyEncrypt SecKeyDecrypt Decryption returns errSecSuccess (status == noErr). There are no Security framework errors. Decryption Code status = SecKeyDecrypt( key, kSecPaddingNone, dataSegment.bytes, dataSegmentRealSize, cipherBuffer, &cipherBufferSize ); status is noErr. However, converting the decrypted data to UTF-8 always returns nil. My Questions Why can SecKeyDecrypt return noErr, yet the resulting data is not valid UTF-8? Is it possible that the decrypted bytes are actually an ASN.1/DER structure rather than the original plaintext? Could this be related to using kSecPaddingNone instead of kSecPaddingPKCS1? Is there anything special about this plaintext (SO202605140735073974) that could trigger this behavior, even though other plaintexts work correctly with the same key pair? Any insights would be greatly appreciated. Thanks!

In my app, I use SecItem to store some data in the Keychain. I’d like to know — when a user sets up a new iPhone and transfers data from the old device, will those Keychain items be migrated or synced to the new device?