In the My Certificates tab, that certificate and its associated private key both show "login" in the Keychain column. I have several other development identities in my keychain and others are working, it's just this one that isn't. The others also have both their certificates and private keys in the login keychain.

Interesting, when I tried to export the cert+key from Keychain Access, I got an error dialog pop up that says: An error has occurred. Unable to export an item. The specified item is no longer valid. It may have been deleted from the keychain. If I click on the certificate in the list, the info pane shows "This certificate is valid", but when I click on the private key nested under it, both the "Kind" and "Usage" fields are blank. Do you think this means I didn't correctly import the key initially? Or that the key was revoked and I need to check with the account holder?

Thanks for the info! I'll try the export/import in a minute, but tried the log export first and thought I'd post it here now in case you see something that points in a particular direction. I believe this is the section of logs resulting from running the MyTrue test: default 2023-10-02 13:14:49.496818 -0700 securityd 0x7fa4ea41e400(0x7fa4ec4095b0) is unlocked; decoding for makeUnlocked() default 2023-10-02 13:14:49.496954 -0700 securityd CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.496983 -0700 securityd CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.497085 -0700 codesign CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.497112 -0700 codesign CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.497131 -0700 codesign caught CssmError: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.497132 -0700 codesign MAC verification failed; something has gone very wrong default 2023-10-02 13:14:49.497133 -0700 codesign key has no integrity, denying access default 2023-10-02 13:14:49.497253 -0700 codesign CSSM Exception: -25304 The specified item is no longer valid. It may have been deleted from the keychain. default 2023-10-02 13:14:49.497267 -0700 codesign error while checking integrity, denying access: CSSM Exception: -25304 The specified item is no longer valid. It may have been deleted from the keychain. default 2023-10-02 13:14:49.497287 -0700 codesign MacOS error: -25304 default 2023-10-02 13:14:49.499564 -0700 securityd CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.499596 -0700 securityd CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.499651 -0700 codesign CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.499676 -0700 codesign CSSM Exception: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.499696 -0700 codesign caught CssmError: -2147415734 CSSMERR_CSP_VERIFY_FAILED default 2023-10-02 13:14:49.499697 -0700 codesign MAC verification failed; something has gone very wrong default 2023-10-02 13:14:49.499701 -0700 codesign key has no integrity, denying access default 2023-10-02 13:14:49.499775 -0700 codesign CSSM Exception: -25304 The specified item is no longer valid. It may have been deleted from the keychain. default 2023-10-02 13:14:49.499788 -0700 codesign error while checking integrity, denying access: CSSM Exception: -25304 The specified item is no longer valid. It may have been deleted from the keychain. default 2023-10-02 13:14:49.502739 -0700 codesign MacOS error: -2070 default 2023-10-02 13:14:49.503076 -0700 codesign Entering exit handler. default 2023-10-02 13:14:49.503077 -0700 codesign Queueing exit procedure onto XPC queue. Any further messages sent will be discarded. activeSendTransactions=0 default 2023-10-02 13:14:49.503125 -0700 codesign Cancelling XPC connection. Any further reply handler invocations will not retry messages default 2023-10-02 13:14:49.503154 -0700 codesign Exiting exit handler. The lines about the key being invalid or deleted are surprising to me since this is the default/login identity, as far as I understand.

Unfortunately, I'm not getting any more info with the verbose flag: $ codesign -vvv -s "Apple Development: ..." -f MyTrue MyTrue: replacing existing signature MyTrue: errSecInternalComponent In case the order mattered, I also tried adding -vvv right before -f and then tried it as the last arg, but both of those gave the same result.