diff --git a/docs/getting_started/user-guide.rst b/docs/getting_started/user-guide.rst
index 8915738..1229e66 100644
--- a/docs/getting_started/user-guide.rst
+++ b/docs/getting_started/user-guide.rst
@@ -588,10 +588,8 @@
 
 -  ``KEY_ALG``: This build flag enables the user to select the algorithm to be
    used for generating the PKCS keys and subsequent signing of the certificate.
-   It accepts 3 values: ``rsa``, ``rsa_1_5`` and ``ecdsa``. The option
-   ``rsa_1_5`` is the legacy PKCS#1 RSA 1.5 algorithm which is not TBBR
-   compliant and is retained only for compatibility. The default value of this
-   flag is ``rsa`` which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
+   It accepts 2 values: ``rsa`` and ``ecdsa``. The default value of this flag
+   is ``rsa`` which is the TBBR compliant PKCS#1 RSA 2.1 scheme.
 
 -  ``KEY_SIZE``: This build flag enables the user to select the key size for
    the algorithm specified by ``KEY_ALG``. The valid values for ``KEY_SIZE``