crypto/rsa: add a test with very different prime sizes

Change-Id: I6a6a46565bdd804790434e2a14216b9f788e5af4
Reviewed-on: https://go-review.googlesource.com/c/go/+/655055
Auto-Submit: Filippo Valsorda <[email protected]>
Reviewed-by: Junyang Shao <[email protected]>
Reviewed-by: Daniel McCarney <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Junyang Shao <[email protected]>

Author: FiloSottile

src/crypto/rsa/rsa_test.go

@@ -1145,3 +1145,46 @@ v/Ow5T0q5gIJAiEAyS4RaI9YG8EWx/2w0T67ZUVAw8eOMB6BIUg0Xcu+3okCIBOs
 	}
 	testEverything(t, k)
 }
+
+func TestLargeSizeDifference(t *testing.T) {
+	// This key has a 768-bit P and a 256-bit Q.
+	k1 := parseKey(testingKey(`-----BEGIN TESTING KEY-----
+MIICmAIBADANBgkqhkiG9w0BAQEFAASCAoIwggJ+AgEAAoGBAOB/V7qbbMLHZSHS
+rU3FLNQJe88wQr5asy813wqlWsCeYUn7Imxv23vDXthpkH/54+CplWDvVri24zhU
+4tHfONSEBWWKTRfQKCW+vrzf+d02rB95lVBrBDSKAUR6w1Xcx9/6ib+kQRDnMl2l
+WZzDgv8jrNPrLGipYBOLcI9/Oh3HAgMBAAECgYBr85AiAX8JIoy0+POxA/GMfIr2
+lERj+IVVXFhGbED5gjUBUn8kz/gOrClZAqgxJKVbdTcxn4KGOM64z427Y24H52zQ
+sCq7RFJ9KDd4s1hAPQImBRUYu2blqDoqxNBQBxLHVUN7vwFp2MGsHzTz7mcx7QNG
+teRbyLhCanUd3UOb4QJhAP5dyjIK1WzKBZ/jSAmjJL64bks4wEEl5eG6e2cTscCH
+RE/OSpHi57dyrxgnBkczt56hOksJFzwmgk4wEM8n/JDOXwIzvAH4w4JWhu169gCW
+8LgxCzJ71xv8+wUUouUTLwIhAOHwcdEAKyLo3K7X1nlYcUOX61yQ1GXRgIROGrsh
+NNjpAmEAuW1nu4k4QmEXLpJB7nyWic3q4T0SsatN5HrMAL1To/U3sDHDHIxbvNiG
+mcXBBuDFp4cC9rY+0OOFtDfH2SveKzW1/uX11T4iT/6Bx9cORCnEe5GNBxVOH6IQ
+34hGo1WTAiEAyCYALW1AyUQPerOpQwWeEIrb7Lw/65KTjqDB/VOFRUECYQCPcc07
+D19OB593kGklAtk1XwGt1W8OmfGIKhGMKzlYhb9MezjaX/3zpO19msSUmSNKszMX
+RpZX4LYz9Ity0nxQ3qZYN6XYNwvr7dCV0E5eS+mgbGWRrf3utdbUkZUNwYE=
+-----END TESTING KEY-----`))
+
+	// This key has a 256-bit P and a 768-bit Q.
+	k2 := parseKey(testingKey(`-----BEGIN TESTING KEY-----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+-----END TESTING KEY-----`))
+
+	if boring.Enabled {
+		t.Skip("BoringCrypto mode returns the wrong error from SignPSS")
+	}
+	testEverything(t, k1)
+	testEverything(t, k2)
+}