diff --git a/sim/mcuboot-sys/Cargo.toml b/sim/mcuboot-sys/Cargo.toml
index 8071ba1..7512e22 100644
--- a/sim/mcuboot-sys/Cargo.toml
+++ b/sim/mcuboot-sys/Cargo.toml
@@ -15,6 +15,9 @@
 # compile with both sig-rsa and sig-ecdsa enabled.
 sig-rsa = []
 
+# Verify RSA-3072 signatures.
+sig-rsa3072 = []
+
 # Verify ECDSA (secp256r1) signatures.
 sig-ecdsa = []
 
diff --git a/sim/mcuboot-sys/build.rs b/sim/mcuboot-sys/build.rs
index 4e293ad..ce4ee25 100644
--- a/sim/mcuboot-sys/build.rs
+++ b/sim/mcuboot-sys/build.rs
@@ -10,6 +10,7 @@
 fn main() {
     // Feature flags.
     let sig_rsa = env::var("CARGO_FEATURE_SIG_RSA").is_ok();
+    let sig_rsa3072 = env::var("CARGO_FEATURE_SIG_RSA3072").is_ok();
     let sig_ecdsa = env::var("CARGO_FEATURE_SIG_ECDSA").is_ok();
     let overwrite_only = env::var("CARGO_FEATURE_OVERWRITE_ONLY").is_ok();
     let validate_primary_slot =
@@ -35,13 +36,23 @@
         conf.define("MCUBOOT_VALIDATE_PRIMARY_SLOT", None);
     }
 
-    // Currently, mbed TLS cannot build with both RSA and ECDSA.
-    if sig_rsa && sig_ecdsa {
-        panic!("mcuboot does not support RSA and ECDSA at the same time");
+    // Currently no more than one sig type can be used simultaneously.
+    if vec![sig_rsa, sig_rsa3072, sig_ecdsa].iter()
+        .fold(0, |sum, &v| sum + v as i32) > 1 {
+        panic!("mcuboot does not support more than one sig type at the same time");
     }
 
-    if sig_rsa {
+    if sig_rsa || sig_rsa3072 {
         conf.define("MCUBOOT_SIGN_RSA", None);
+        // The Kconfig style defines must be added here as well because
+        // they are used internally by "config-rsa.h"
+        if sig_rsa {
+            conf.define("MCUBOOT_SIGN_RSA_LEN", "2048");
+            conf.define("CONFIG_BOOT_SIGNATURE_TYPE_RSA_2048", None);
+        } else {
+            conf.define("MCUBOOT_SIGN_RSA_LEN", "3072");
+            conf.define("CONFIG_BOOT_SIGNATURE_TYPE_RSA_3072", None);
+        }
         conf.define("MCUBOOT_USE_MBED_TLS", None);
 
         conf.include("mbedtls/include");
@@ -114,7 +125,7 @@
         conf.file("../../boot/bootutil/src/encrypted.c");
         conf.file("csupport/keys.c");
 
-        if sig_rsa {
+        if sig_rsa || sig_rsa3072 {
             conf.file("mbedtls/library/sha256.c");
         }
 
@@ -141,7 +152,7 @@
 
     if sig_rsa && enc_kw {
         conf.define("MBEDTLS_CONFIG_FILE", Some("<config-rsa-kw.h>"));
-    } else if sig_rsa || enc_rsa {
+    } else if sig_rsa || sig_rsa3072 || enc_rsa {
         conf.define("MBEDTLS_CONFIG_FILE", Some("<config-rsa.h>"));
     } else if sig_ecdsa && !enc_kw {
         conf.define("MBEDTLS_CONFIG_FILE", Some("<config-asn1.h>"));
@@ -150,7 +161,7 @@
     }
 
     conf.file("../../boot/bootutil/src/image_validate.c");
-    if sig_rsa {
+    if sig_rsa || sig_rsa3072 {
         conf.file("../../boot/bootutil/src/image_rsa.c");
     } else if sig_ecdsa {
         conf.file("../../boot/bootutil/src/image_ec256.c");
diff --git a/sim/mcuboot-sys/csupport/keys.c b/sim/mcuboot-sys/csupport/keys.c
index 6e4f3f5..23bdb21 100644
--- a/sim/mcuboot-sys/csupport/keys.c
+++ b/sim/mcuboot-sys/csupport/keys.c
@@ -22,6 +22,7 @@
 #include <mcuboot_config/mcuboot_config.h>
 
 #if defined(MCUBOOT_SIGN_RSA)
+#if MCUBOOT_SIGN_RSA_LEN == 2048
 #define HAVE_KEYS
 const unsigned char root_pub_der[] = {
     0x30, 0x82, 0x01, 0x0a, 0x02, 0x82, 0x01, 0x01, 0x00, 0xd1, 0x06, 0x08,
@@ -49,6 +50,62 @@
     0xc9, 0x02, 0x03, 0x01, 0x00, 0x01
 };
 const unsigned int root_pub_der_len = 270;
+#elif MCUBOOT_SIGN_RSA_LEN == 3072
+#define HAVE_KEYS
+const unsigned char root_pub_der[] = {
+    0x30, 0x82, 0x01, 0x8a, 0x02, 0x82, 0x01, 0x81,
+    0x00, 0xb4, 0x2c, 0x0e, 0x98, 0x58, 0x10, 0xa4,
+    0xa7, 0x58, 0x99, 0x7c, 0x01, 0xdd, 0x08, 0x2a,
+    0x28, 0x34, 0x33, 0xf8, 0x96, 0x1a, 0x34, 0x20,
+    0x5d, 0x45, 0xc8, 0x71, 0x26, 0x25, 0xe5, 0xd2,
+    0x96, 0xea, 0x7b, 0xb1, 0x15, 0xaa, 0xa6, 0x8a,
+    0x63, 0x22, 0x8b, 0x2d, 0x4e, 0x81, 0x73, 0xbf,
+    0x6e, 0x15, 0x68, 0x8c, 0x1a, 0xf4, 0xef, 0x2a,
+    0x8f, 0x8c, 0x22, 0x9e, 0x71, 0x57, 0x4b, 0xde,
+    0x0f, 0x7e, 0x72, 0xd3, 0x7a, 0xb8, 0xa7, 0x1d,
+    0x44, 0xad, 0x87, 0x00, 0x83, 0x5c, 0xfd, 0x73,
+    0x05, 0x72, 0x46, 0x3f, 0x8b, 0xf9, 0x10, 0x00,
+    0xd8, 0x6e, 0xcc, 0x85, 0xed, 0xf9, 0x49, 0xdb,
+    0x78, 0x36, 0x80, 0x49, 0x38, 0x76, 0xdd, 0x5f,
+    0x54, 0x04, 0xda, 0x8c, 0x34, 0xa7, 0x2b, 0x13,
+    0x25, 0x6f, 0xd1, 0x15, 0x4f, 0xad, 0xc2, 0xe1,
+    0xa5, 0xd2, 0x4e, 0x57, 0x0c, 0x7e, 0x9c, 0x9b,
+    0xba, 0x4e, 0x68, 0xb2, 0xe0, 0x25, 0x02, 0xaa,
+    0x00, 0xd3, 0xb4, 0xcc, 0x2f, 0x78, 0xe5, 0xbe,
+    0x47, 0x67, 0x1f, 0xc8, 0x6e, 0x22, 0x6c, 0x5e,
+    0x61, 0xb6, 0x9a, 0xcd, 0xe5, 0xa8, 0xba, 0x7a,
+    0x80, 0x13, 0x1b, 0x17, 0x2e, 0x96, 0xed, 0xcf,
+    0xb3, 0x9b, 0xe4, 0x1c, 0xe8, 0xad, 0xa7, 0xf6,
+    0x3a, 0x51, 0x66, 0x5e, 0x99, 0x8e, 0x87, 0xee,
+    0x60, 0x25, 0xf8, 0x8d, 0xbe, 0xce, 0xa4, 0xa8,
+    0xca, 0x93, 0x6c, 0xd7, 0xbf, 0xd4, 0x73, 0x33,
+    0x8d, 0x44, 0x85, 0xcc, 0x73, 0x30, 0x08, 0x9c,
+    0x4d, 0xb2, 0xaa, 0x5a, 0x6c, 0x6f, 0x7b, 0xab,
+    0xb7, 0xb3, 0x7c, 0xc3, 0xfb, 0xe7, 0xca, 0xc4,
+    0xf8, 0x9a, 0x6f, 0xcb, 0xbb, 0x5b, 0x82, 0xe7,
+    0x7a, 0xe8, 0x19, 0xfd, 0x2f, 0x11, 0x22, 0xfb,
+    0x7f, 0x76, 0x8c, 0x6b, 0x94, 0xa4, 0x09, 0x4f,
+    0xa5, 0x6a, 0x77, 0x51, 0xeb, 0xa7, 0x7e, 0xda,
+    0x87, 0x06, 0xee, 0xdc, 0xbe, 0xd1, 0xea, 0x1a,
+    0x40, 0x1d, 0x1b, 0xff, 0x1a, 0xb1, 0x51, 0x7c,
+    0x12, 0xb0, 0xf3, 0xf6, 0x83, 0x01, 0x9c, 0xe7,
+    0x0c, 0x99, 0xbf, 0xac, 0x68, 0x58, 0x72, 0xa4,
+    0xb0, 0x59, 0x85, 0xee, 0x85, 0xac, 0x2a, 0x22,
+    0xf4, 0xcf, 0x15, 0x08, 0x80, 0x1f, 0x0d, 0xd0,
+    0x1e, 0xa0, 0xa0, 0x94, 0xc8, 0xf7, 0xfa, 0x65,
+    0xdd, 0x52, 0xe8, 0x96, 0x37, 0x23, 0x30, 0x57,
+    0x36, 0xe6, 0x9d, 0xf4, 0x0c, 0x4a, 0x05, 0x75,
+    0x1f, 0xad, 0x01, 0xca, 0xb7, 0x6d, 0x8c, 0x43,
+    0x74, 0x06, 0x0a, 0x81, 0xf3, 0x01, 0x62, 0xff,
+    0xf7, 0xf5, 0x5f, 0xaf, 0xe7, 0x2b, 0x0e, 0xf8,
+    0x81, 0xb5, 0x65, 0xdd, 0x01, 0xd9, 0x9f, 0x07,
+    0x17, 0x8a, 0x18, 0xcf, 0x23, 0x6e, 0x88, 0x65,
+    0x91, 0xb5, 0x7b, 0xd3, 0xb0, 0x2d, 0xaf, 0x93,
+    0x66, 0x63, 0x74, 0xac, 0x5a, 0xe6, 0x73, 0xde,
+    0x3b, 0x02, 0x03, 0x01, 0x00, 0x01,
+};
+const unsigned int root_pub_der_len = 398;
+#endif
 #elif defined(MCUBOOT_SIGN_EC256)
 #define HAVE_KEYS
 const unsigned char root_pub_der[] = {