public static SealedSharedKey fromTokenString(String tokenString) {
        verifyInputTokenStringNotTooLarge(tokenString);
        byte[] rawTokenBytes = Base62.codec().decode(tokenString);
        return fromSerializedBytes(rawTokenBytes);
    }
Attempts to unwrap a SealedSharedKey opaque token representation that was previously
created by a call to toTokenString().
security-utils/src/main/java/com/yahoo/security/SealedSharedKey.java