While generating the certificate signing request , the 'Key Size' options only displays 512-bit and the Key Type is restricted to RSA only.    Run the command 'get system status' to check the license status of the FortiGate.  FortiGate-VM64-AZURE v7.6.3,build3510,250415 (GA.F)
First GA patch build date: 240724
Security Level: Low
Virus-DB: 1.00000(2018-04-09 18:07)
Extended DB: 1.00000(2018-04-09 18:07)
Extreme DB: 1.00000(2018-04-09 18:07)
AV AI/ML Model: 0.00000(2001-01-01 00:00)
IPS-DB: 6.00741(2015-12-01 02:30)
IPS-ETDB: 6.00741(2015-12-01 02:30)
IPS-MLDB: 0.00000(2001-01-01 00:00)
APP-DB: 6.00741(2015-12-01 02:30)
Proxy-IPS-DB: 6.00741(2015-12-01 02:30)
Proxy-IPS-ETDB: 6.00741(2015-12-01 02:30)
Proxy-APP-DB: 6.00741(2015-12-01 02:30)
FMWP-DB: 0.00000(2001-01-01 00:00)
IPS Malicious URL Database: 1.00001(2015-01-01 01:01)
IoT-Detect: 0.00000(2022-08-17 17:31)
OT-Detect-DB: 0.00000(2001-01-01 00:00)
OT-Patch-DB: 0.00000(2001-01-01 00:00)
OT-Threat-DB: 6.00741(2015-12-01 02:30)
IPS-Engine: 7.01040(2025-04-09 17:33)
Timezone DB Version: 1.011
Timezone DB IANA Version: 2025c
Serial-Number: FGVM4VTM25XXXXX
License Status: Valid
VM Resources: 4 CPU/4 allowed, 16037 MB RAM
Cloud Resource Group: rg-cus-fw-connect
Log hard disk: Available
Hostname: vmcusfw-fgt-1
Operation Mode: NAT
Current virtual domain: root
Max number of virtual domains: 2
Virtual domains status: 1 in NAT mode, 0 in TP mode
Virtual domain configuration: disable
FIPS-CC mode: disable
Current HA mode: standalone
License Status: Low-Encryption(LENC)
Branch point: 3510
Release Version Information: GA
FortiOS x86-64: Yes
System time: Mon Mar 2 10:08:48 2026
Last reboot reason: power cycle
 If the license status displays Low-Encryption (LENC), this behavior is expected, as the LENC license restricts the device to lower encryption key sizes and ciphers.  The LENC license utilizes TLS version 1.0, which is deprecated and also no longer supported by FortiGuard Server. As a result, validation attempts are unsuccessful due to the inability to negotiate a more secure encryption cipher with this license. See this article:
Troubleshooting Tip: Connectivity issue with FortiGuard servers due to SSL_connect failure (LENC license).
To enable higher encryption key sizes and ciphers, a standard (non-LENC) license entitlement must be purchased through a Fortinet partner to upgrade the device to a full encryption license. Once the new license is obtained and applied to the FortiGate device, verify the license status by running the 'get system status' command again.
 After upgrading to a standard license, the device will support generating certificates with higher encryption ciphers and key sizes. | 
